UGC NET Paper 2: Geography 18th Dec 2018 (Previous Year Paper)

the correct answer is option 4 :(a) - (iii), (b) - (iv), (c) - (i), (d) - (ii)

Important Points

Large Raindrops - (iii) 23 km/hr:

• Large raindrops are relatively heavy and fall at a faster speed compared to other types of droplets. They have a fall velocity of approximately 23 km/hr.

Drizzle Droplets - (iv) 0.3 km/hr:

• Drizzle droplets are very fine and small, and they fall slowly due to their low mass. Their fall velocity is only about 0.3 km/hr.

Large Cloud Droplets - (i) 7 km/hr:

• Large cloud droplets, while larger than drizzle droplets, are still much smaller and lighter than raindrops. They fall at a moderate speed, around 7 km/hr.

Typical Raindrops - (ii) 33 km/hr:

• Typical raindrops, which are neither extremely large nor extremely small, have a relatively high fall velocity of approximately 33 km/hr. This makes them fall faster than the other types of droplets listed here.

So, when we match the types of water droplets with their respective fall velocities, we find that Option 4 correctly represents the characteristics of these droplets and their fall speeds:

(a) Large raindrops - (iii) 23

(b) Drizzle droplets - (iv) 0.3

(c) Large cloud droplets - (i) 7

(d) Typical raindrops - (ii) 33

Therefore, Option 4 accurately reflects the fall velocities of these different types of water droplets, making it the correct answer.

Key Points Assertion (A): Mid-latitude cyclones are low-pressure systems traveling from east to west across the middle latitudes in both hemispheres.

Mid-latitude cyclone:

• A temperate cyclone is referred to as mid-latitude depressions, extra-tropical cyclones, frontal depressions, and wave cyclones.
• Temperate cyclones are active above the mid-latitudinal region between 35o to 65o latitudes in both hemispheres.
• The direction of movement is blowing from west to east and is more pronounced in the winter seasons.
• It is in these latitude zones the polar and tropical air masses meet and form fronts.

Hence, the assertion is incorrect as the direction of movement is blow from west to east.

Reason (R): Most mid-latitude cyclones have a cold front and a warm front.

Frontal theory of temperate cyclone:

• Polar Front Theory According to this theory, the warm-humid air masses from the tropics meet the dry-cold air masses from the poles and thus a polar front is formed.
• It creates a surface of discontinuity between two air masses.
• Such conditions occur between sub-tropical highs and sub-polar lows.
• The cold air is denser and heavier as the intermolecular space of the cold air is smaller.
• It always occupies the lower ground space.
• Due to this reason, warm sub-tropical air is pushed up.
• There is an interaction between the two air masses depending upon their nature in terms of temperature and moisture conditions.
• This interaction of cold and warm air masses creates instability and low pressure is created at the junction particularly in the center of interactions.
• The center of interaction is that zone where the warm and cold fronts are differentiated.
• Latter on this point develops as the eye of the cyclone.

Hence, the reason is correct as the center of the interaction of cold and warm front develops the cyclone.

Therefore, (A) is false, but (R) is true.

• A continental shelf is the edge of a continent that lies under the ocean. Continents are the seven main divisions of land on Earth. A continental shelf extends from the coastline of a continent to a drop-off point called the shelf break. From the break, the shelf descends toward the deep ocean floor in what is called the continental slope.
• In western South America, a large coastal plain lies between the Andes Mountains and the Pacific Ocean. In the United States, coastal plains can be found along the Atlantic Ocean and the Gulf of Mexico.
• Western south America where coast is extremely mountainous, continental shelf are almost absent.

• The term craton is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable.
• Cratons can be described as shields, in which the basement rock crops out at the surface, and platforms, in which the basement is overlaid by sediments and sedimentary rock.
• The word craton was first proposed by the Austrian geologist Leopold Kober in 1921 as Kratogen, referring to stable continental platforms, and orogen as a term for mountain or orogenic belts.
• Igneous rock such as granite is associated with Cratons.

Key Points

Assertion (A): Wind is the result of only the vertical differences in atmospheric pressure.

The origin of wind:

• The wind is the movement of air caused by the uneven heating of the Earth by the sun.
• Differences in atmospheric pressure generate winds.
• At the Equator, the sun warms the water and land more than it does the rest of the globe.
• Warm equatorial air rises higher into the atmosphere and migrates toward the poles.
• This is a low-pressure system. At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air.
• This is a high-pressure system.
• Winds generally blow from high-pressure areas to low-pressure areas
• The Coriolis effect causes some winds to travel along the edges of the high-pressure and low-pressure systems.
• These are called geostrophic winds.

Hence, the assertion is incorrect.

Reason (R): Wind is nature's attempt to balance inequalities in air pressure.

• Air flows from areas of higher pressure to areas of lower pressure.
• The wind is basically nature's attempt to balance inequalities in air pressure.
• Since unequal heating of the Earth's surface generates these pressure differences, solar energy is the ultimate energy source for most wind.

Hence, the reason is correct.

Therefore, (A) is false, but (R) is true.

Key Points

• The partitioning of the world into ‘natural’ zoological regions, defined as areas with a consistency and distinctiveness of the fauna and flora, has attracted the attention of zoogeographers since the early 19th century
• Zoo-geographical regions are characterized on the basis of distinctive animal life. Specifically, where the world's biogeographical regions are concerned, it makes sense to test their accuracy using the same groups of organisms used to delimit them in the first place.
• Wallace (1876) used a simple quantitative method to delimit global faunal regions based on the distribution of vertebrates in general, with a major focus on non-volant mammals, and further subdivided each of the six large regions into four subregions
• A.R. Wallace described six major zoo-geographical regions of the world.
• According to A.R. Wallace six major zoo-geographical regions are Palaearctic Region, Nearctic Region, Neotropical region, Oriental Region, Ethiopian Region, and Australian Region.

Key Points

 Assertion (A):  The most stable conditions occur during a temperature inversion when the temperature actually increases with height.

The concept of temperature inversion:

• It is a reversal of the normal behavior of temperature, i.e increasing with the increasing height in the troposphere.
• Under this meteorological phenomenon, a layer of warm air lies over the cold air layer.

Suitable conditions for temperature inversion:

• Long nights, so that the outgoing radiation is greater than the incoming radiation.
• Clear skies, which allow the unobstructed escape of radiation.
• Calm and stable air, so that there is no vertical mixing at lower levels.

Hence, the assertion is correct.

Reason (R): Temperature inversion leads to greater vertical air movement.

• It is caused by static atmospheric conditions while sometimes, it occurs due to horizontal or vertical movement of air.
• Temperature inversion is usually of short duration but quite common nonetheless.

Hence, the reason is incorrect.

Therefore, (A) is true, but (R) is false.

Coral polyps are the individual corals that are found on the calcium carbonate exoskeletons of their ancestors. Corals can be found in all the oceans but the biggest coral reefs are mostly found in the clear, shallow waters of the tropics and subtropics. The largest of these coral reef systems, The Great Barrier Reef in Australia, the largest coral reef is more than 1,500 miles long.

Key Points

Growth conditions for Coral Reefs

• The temperature of the water should not be below 20°C.
• The most favorable temperature for the growth of the coral reefs is between 23°C to 25°C. The temperature should not exceed 35°C.
• Corals can survive only under saline conditions with an average salinity between 27% to 40%.
• Coral reefs grow better in shallow water having a depth of less than 50 m. The depth of the water should not exceed 200m.
• Corals need access to sunlight for photosynthesis, so the water where they grow needs to be shallow and clear.
• Excess of sediment in the water can smother the coral polyps and too much fresh water kills them. That is why coral reefs don't grow close to the mouths of rivers.

Important Points

• Seamounts and Guyots are volcanoes that have built up from the ocean floor, sometimes to sea level or above.
• Guyots are seamounts that have been built above sea level.
• Erosion by waves destroyed the top of the seamount resulting in a flattened shape.
• Due to the movement of the ocean floor away from oceanic ridges, the seafloor gradually sinks and the flattened guyots are submerged to become undersea flat-topped peaks.
• We know that the tops of guyots were once at the surface because they contain evidence of fossils such as coral reefs that only live in shallow water.
• Seamounts conversely represent volcanoes that did not reach sea level so their tops remain intact and are shaped like volcanoes on land.

Hence, Guyots and seamounts are not supporting for speedy growth of coral reefs.

The air quality index (AQI) is an index for reporting air quality on a daily basis. It is a measure of how air pollution affects one's health within a short time period. The purpose of the AQI is to help people know how the local air quality impacts their health. The higher the AQI value, the greater the level of air pollution and the greater the health concerns. AQI quickly disseminates air quality information in real-time.​

The Environmental Protection Agency (EPA) calculates the AQI for five major air pollutants, for which national air quality standards have been established to safeguard public health.

1. Ground-level ozone
   
2. Particle pollution/particulate matter (PM2.5/pm 10)
   
3. Carbon Monoxide
   

4. Sulfur dioxide

5. Nitrogen dioxide

Air Quality Index Categories

• Good (0–50) - Minimal Impact
• Satisfactory (51–100) - May cause minor breathing difficulties in sensitive people.
• Moderately polluted (101–200) - May cause breathing difficulties in people with lung disease like asthma, and discomfort to people with heart disease, children and older adults.
• Poor (201–300) - May cause breathing difficulties in people on prolonged exposure, and discomfort to people with heart disease
• Very Poor (301–400) - May cause respiratory illness in people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.
• Severe (401-500) - May cause respiratory issues in healthy people, and serious health issues in people with lung/heart disease. Difficulties may be experienced even during light physical activity.

Geological eras

• Geologists divide the periods from the Earth’s formation up until now into a number of eras based on the changes that happened in each of them.
• We are currently in the Holocene era, which started around 11,700 years ago when the Ice Age ended.
• More recently though, a number of scientists have argued that because of the nuclear bomb testings of the 1950’s and population explosion, humans have entered a new era, called the Anthropocene.
• They argue that with more than seven billion people, human activity has drastically influenced nature and the extinction of a number of wildlife.
• The Earth is no stranger to disappearing life forms. There are have been many periods of extinction, from when the first organism emerged on Earth until today.
• However, according to fossil records, only five eras have drastically reduced the population of living beings on earth to warrant the label of mass extinction.

First period of extinction

• Entering early to mid period of the Ordovician Era, the Earth was still warm with an ideal humidity level for living. However, towards the end of the period - around 443 million years ago - everything changed suddenly, when the old continent Gondwana reached the South Pole. The temperature dropped drastically and ice formed everywhere, lowering the water level.
• Subsequently, the level of carbon dioxide in the atmosphere and in the sea dropped, causing the number of plants to decrease dramatically and an ecosystem chaos ensued because certain plants, used as sources of food, became scarce.
• Some 86% of the population of living beings disappeared within three million years. Some of the organisms affected by the first extinction were Brachiopods, Conodonts, Acritarchs, Bryozons, and also Trilobites that lived in the ocean.

Second period of extinction

• The second period of extinction, during the Devon Age, happened around 359 million years ago. A relentless meteor shower is believed to be one of the causes of mass extinction. Other causes include a drastic decrease in oxygen levels globally, the increased activity of tectonic plates, and climate change. These changes caused around 75% of living creatures to die.
• Extinction in this period impacted life in the sea which, at the time, was dominated by corals and stromatoporoids.

Third period of extinction

• The third period of extinction, around 251 million years ago, during the Permian Age, was the biggest and worst that ever happened on Earth.
• The formation of the giant continent Pangea caused immense changes in geology, climate and the environment. Volcanic eruptions that continued for 1 million years released around 300 million square kilometres of lava while more than 1750 metres of sediment was formed in the Siberian Traps.
• The eruptions burned forests four times the size of Korea. It produced large volumes of carbon dioxide that caused global warming. As a result, frozen methane below the sea melted, producing a global warming effect 20 times more powerful than carbon dioxide.
• The global warming lasted for approximately 10 million years. A terrible mass extinction was inevitable. Only 5% of the population of life on Earth survived and 95% perished from massive drought, lack of oxygen and acid rain that made plants unable to survive.

Fourth period of extinction

• The fourth period of extinction happened around 210 million years ago, during the Late Triassic Age.
• The slow splitting of Pangea caused volcanoes to form in the Central Atlantic Magmatic Province. After a spike in atmospheric carbon dioxide, global warming started again, with scientists speculating it lasted as long as eight million years.
• This caused coral and [conodonts](https://australianmuseum.net.au/what-are-conodonts], an eel-like ancient sea creature to face serious crisis. Coral-based creatures did not survive.
• A meteor rain also hastened the destruction in this period: Around 80% of living creatures, including reptiles died, with some 20% of the creatures that became extinct sea-based lifeforms.
• Additionally, a number of creatures that lived on land that died in this period were pseudosuchia, crocodylomorphs, theropods and several large amphibians.

Fifth period of extinction

• The fifth period of extinction happened around 65 million years ago and is more popularly known as Cretaceous-Tertiary extinction. It was the fastest period of mass extinction, occurring over one to 2.5 million years.
• It’s possibly the most known period of mass extinction because this was when dinosaurs were wiped out from the face of the earth. Scientists believe a meteor fall in today’s Gulf of Mexico compounded with high volcanic activity which produced a significant amount of carbon dioxide, killed half of the earth’s living population.

Confusion Points In the official paper provided by UGC, the correct matching is (a) - 4, (b) - 3, (c) - 2, (d) - 1. After analyzing the content in both lists, it is clearly understood that the correct matching should be (a) - 3, (b) - 4, (c) - 2, (d) - 1. So the option was modified accordingly.

Important Points

Key Points

The famous book 'Almagest'

• Almagest, an astronomical manual written about ad 150 by Ptolemy (Claudius Ptolemaeus of Alexandria).
• It served as the basic guide for Islamic and European astronomers until about the beginning of the 17th century.
• Its original name was Mathematike Syntaxis (“The Mathematical Arrangement”)
• Almagest arose as an Arabic corruption of the Greek word for greatest (megiste).
• It was translated into Arabic about 827 and then from Arabic to Latin in the last half of the 12th century.
• Subsequently, the Greek text circulated widely in Europe, although the Latin translations from Arabic continued to be more influential.
• The Almagest is divided into 13 books.
• Book 1 gives arguments for a geocentric, spherical cosmos and introduces the necessary trigonometry, along with a trigonometry table, that allowed Ptolemy in subsequent books to explain and predict the motions of the Sun, Moon, planets, and stars.

Hence, the famous text on classical astronomy entitled "Almagest" was authored by Ptolemy.

The major difference between natural and man-made air pollution is that continuous or temporary natural events cause natural air pollution, but human activities are responsible for man-made pollution. We can't prevent natural air pollution from sources like volcanoes, but we can reduce man-made pollutants and their consequences: respiratory diseases, acid rain and global warming.

Natural Sources of Air Pollution

• Natural air pollutants include radon, fog and mist, ozone, ash, soot, salt spray, spores released by plants, windblown dust and volcanic and combustion gases.
• Radon is a radioactive gas that seeps from the ground in some areas, and fog and mist are both dense water vapor at ground level that obscures vision.
• Ozone, a chemical formed naturally by the action of sunlight on oxygen, is a pollutant at ground level but beneficial in the upper atmosphere. A molecule made of three oxygen atoms, ozone shields the Earth from harmful ultraviolet rays from the sun, but it damages plants and causes breathing problems in the lower atmosphere.
• Volcanic eruptions and forest, swamp and grass fires launch soot and ash into the atmosphere, which reduces sunlight and lowers temperatures. Eruptions and fires also produce carbon dioxide, carbon monoxide and other polluting gases.
• The large number of nuclear weapons tests carried out in the atmosphere and underground during 1945–2013 (the last nuclear test was performed by North Korea) was responsible for the current environmental contamination with radioactive waste which resulted in ecologically and socially destroyed sites, due to high levels of radioactivity.
• The 2000 Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly states that:
  

“The main man-made contribution to the exposure of the world's population [to radiation] has come from the testing of nuclear weapons in the atmosphere, from 1945 to 1980. Each nuclear test resulted in unrestrained release into the environment of substantial quantities of radioactive materials, which were widely dispersed in  the atmosphere and deposited everywhere on the Earth’s surface.”

Afro-Alpine belt

• The highest mountains in equatorial East Africa host a unique vegetation having growth forms that display convergent evolution with plants in South America’s páramo.
• These peaks include the volcanic Mt. Kilimanjaro, the highest mountain on the African continent at 19,340 ft asl; Mt. Kenya (17,058 ft asl); Mt. Elgon (14,177 ft); and Mt. Meru (14,977), all on the eastern rift of the East African Rift zone in Kenya and Tanzania, as well as the massive Virunga volcanoes of the western or Albertine rift.

Ericaceous Belt

• Fire is the most frequent disturbance in the Ericaceous Belt (ca 3000–4300 m.a.s.l.), one of the most important plant communities of tropical African mountains.
• They are also found on the crests and summits of smaller mountains (especially those that are situated close to the ocean or a large lake) or locally on shallow soils within the Afromontane forest belt. Where the ground is not very rocky and has been protected for several years, such as on wetter mountains as the Ruwenzori Mts., almost impenetrable thickets of 3 to 13 m are formed.

Bamboo Zone

• Bamboo zone found above the lowland forest or montane forest.

Lowland Forest

• Lowland forest are dense evergreen forests, extending from about 2200 to 3500 metres.

The concept of paradigm was propounded by Kuhn.

Key Points The concept of Paradigm by Kuhn:

• Thomas Kuhn wrote, “The Structure of Scientific Revolution” (1962).
• **Kuhn fathered, defined, and popularized the concept of **“paradigm shift”.
• It is a fundamental change in the basic concepts and experimental practices of a scientific discipline.
• Thomas Kuhn argued that science does not evolve gradually towards truth.
• Science has a paradigm that remains constant before going through a paradigm shift when current theories can’t explain some phenomenon, and someone proposes a new theory.
• A scientific revolution occurs when:
• the new paradigm better explains the observations, and offers a model that is closer to the objective, external reality; and
• the new paradigm is incommensurate with the old.
• For example, Lamarckian evolution was replaced with Darwin’s theory of evolution by natural selection.

Additional Information

• Immanuel Kant: Father of exceptionalism
• Peter Haggett: locational analysis in geography
• Richard Peet: The Development of Radical Geography in the United States

The nomothetic approach in geography emphasizes Lawmaking study.

Key PointsNomothetic approach:

• The term “nomothetic” comes from the Greek word “nomos” meaning “law”.
• Psychologists who adopt this approach are mainly concerned with studying what we share with others (i.e. similarities between people).
• Therefore, the nomothetic approach involves establishing laws or generalizations that apply to all people.
• Nomothetic is based on what Kant described as a tendency to generalize, and is typical for the natural sciences.
• It describes the effort to derive laws that explain types or categories of objective phenomena, in general.

Hence, the nomothetic approach involves trying to make generalizations about the world and understand large-scale social patterns.

• Yardangs are sharp and sinuous ridges that extend parallel to the wind direction. Yardangs are formed by the action of the wind in the arid region. They are mainly found in Arebian desert (Caliche limestone), Sinai Peninsula (Nubian Sandstone), Taklimakan Desert, Mojave Desert etc.
• Yardang made of Eocene limestone are found in Jaisalmer Basin. The Jaisalmer Basin occupies an area of 42000 sq. km and much of it is covered by the modern sand-dunes.
• Yardang made of clay are found in Dasht-e Khash desert of Nimruz Province in Afghanistan.

• Al-Masudi correlated the colour of ocean water and its salinity. According to Al-Masudi the salt in the seas and oceans comes from the land.
• He also contributed to cosmology, meteorology, oceanography, study of landforms, and astronomy.
• Kitab-Muraj-al- Dhahab, Kital-al-Tanbhwal-Ishraf, and Kitab-Akhbar-al-Zaman are his famous work.
• He was an important scholar who hailed from Bagdad. Al-Masudi described the weather conditions of the places he visited or sailed through ad also pointed out that the salt in the seas comes from the land.
• He had a clear idea of the spherical shape of the earth. In the field of human geography he tried to study the relationship between human beings and the environment and explained the impact of environment on the mode life and attitude of people (environmental determinism). He even divided the world into seven regions on the basis of language.

The Swedish geographer Torsten Hagerstrand created time geography in the mid-1960s based on ideas he had developed during his earlier empirical research on human migration patterns in Sweden. He sought "some way of finding out the workings of large socio-environmental mechanisms" using "a physical approach involving the study of how events occur in a time-space framework". Hagerstrand was inspired in part by conceptual advances in spacetime physics and by the philosophy of physicalism.

In geography concept of Time–space was introduced by Torsten Hagerstrand. It provides a method of mapping spatial movements through time. According to Hagerstrand reason for Time–space concept in geography are:

• space and time are scarce resources which individuals draw on to achieve their goals
• achieving a goal is subject to constraints
• these constraints interact to demarcate probability boundaries
• that choices are made within these boundaries.

• ‘A hundred years of geography’ is authored by Thomas Walter Freeman. This book traces the progress geography as a subject made over a century.
• It contains a synoptic view of the development of the various aspects of geography, showing how the field has been differentiated from associated disciplines and how it has differentiated and specialized within itself.
• It contains a synoptic view of the development of the various aspects of geography, showing how the field has been differentiated from associated disciplines and how it has differentiated and specialized within itself.
• The book also offers two important reference tools: a bibliography of the important geographical works published throughout the world, and biographical sketches of ninety important geographers.

• Gould and White developed the concept of mental map. In behavioral geography, a mental map is a person's point-of-view perception of their area of interaction.
• Mental maps can also be decoded to reveal biases of objectified cartographic knowledge such as socio-spatial hierarchies that structure the world, or to explore ways in which collectives and individuals orient themselves in their environment, or to understand how they perceive the world.

Key Points

Hence, the correct matching is (a) - 2, (b) - 1, (c) - 4, (d) - 3

Key Points

Assertion (A):  Central Business District (CBD) of a city has a high concentration of wholesale stores, offices, and cultural and recreational activities.

The concept of CBD:

• The term Central Business District (CBD) is a widely used term in commercial real estate and is defined as the functional area of a city that has the maximum concentration of commercial, retail, and business centers.
• Geographically, it coincides with the city center and is the focal point for the transportation networks of the city.
• It has maximum urban density than other districts of the town and offers a healthy environment for carrying out various commercial activities.
• Today, CBDs are a diverse region in metro cities that not only include retail spaces, commercial, offices, financial institutions, government centres, and medical centres, but also entertainment hubs, restaurants, hotels, and residential area

Hence, the assertion is correct.

Reason (R): Prices and demand of real increases as distance towards CBD reduces.

Price and demand relationship:

• In ancient times, CBDs were the market squares where merchants and customers gathered to sell and buy things.
• However, as cities evolved, land scarcity and increasing demand reduced horizontal expansions and gave way to vertical developments.
• The relationship of land price and distance to CBD is significant and negative, which means indicating the decreasing of land price by increasing distance from the CBD.
• Market price gives the same result as the appraised price which is the effect of distance on land values is significant and negative.

Hence, the reason is also correct.

Therefore, Both (A) and (R) are true and (R) is the correct explanation of (A).

The above figure is representing the Bridging point settlement site.

Key PointsBridging point settlement site:

• A settlement site where a river is narrow or shallow enough to be bridged.
• The bridge becomes a routeing centre and trading centre, the natural location for a market.
• It is also a good defensive site.
• The lowest bridging point on a river is the bridge nearest to the sea; this site is ideal for a river port settlement.

Additional Information

• Drypoint settlement site: a settlement site on dry land surrounded by low, wet ground; this was good for defence.
• The wet point settlement site: a settlement location where the main advantage is a water supply in an otherwise dry area e.g. at a spring where an impermeable clay valley meets the foot of permeable limestone or chalk hills.
• Defense settlement site: a settlement that usually grew at or around a fort or castle on top of a hill, although river meander bends, bridges, dry-point sites, and coastal sites with cliffs were also good for defense.

Key Points

Hence, the correct matching is (a) - 3, (b) - 1, (c) - 2, (d) - 4

Key Points 

Hence, the correct matching is (a) - 4, (b) - 1, (c) - 3, (d) - 2

Central Place Theory:

• The theory was postulated by Walther Christaller
• It was published in his book “Central Place in Southern Germany” (Die zentralen Orte in Suddeutschland) in 1933 and translated in English in 1966.
• It is a normative theory
• Based on the data obtained from Bavaria in South Germany
• No of settlements are represented by ‘K’
• There are two basic concepts:
• Threshold: it is the minimum population requires for the establishment of a service
• Range: the maximum distance one can travel for a single amenity/good/service

The given figure is showing the K = 7 or Administrative Principle.

The administrative principle:

• Settlements are nested according to sevens
• The market areas of the smaller settlements are completely enclosed within the area of the larger settlement
• Tributary areas must be allocated exclusively to a single higher-order place
• Efficiency administration is the control principle in this hierarchy
• Here K=7, K= 1+6

Principles of Central Place Theory:

Delhi:

• Delhi is the National Capital Territory and it is bordered by Haryana on three sides and by Uttar Pradesh in the east.
• As per the 2011 Census, the sex ratio of Delhi was 868 females per 1000 males.
• As per the 2011 census, Delhi has the highest density of population with 11,320 Density / Km2 among all states and union territories.
• Delhi is the most urbanized Union Territories of India in 2011 followed by Chandigarh. Himachal Pradesh is the least urbanized state followed by Bihar.

Key Points

Gravity model:

• The Gravity Model is based on Newton's law of gravitation.
• It relies on the population and distance.
• The gravity model was expanded by William J. Reilly in 1931 into Reilly's law of retail gravitation to calculate the breaking point between two places where customers will be drawn to one or another of two competing commercial centers.
• The Gravity Model holds that the interaction between two places can be determined by the product of the population of both places, divided by the square of their distance from one another.

Potential model:

• The level of interaction between one location and all the others is measured by the summation of the attributes of each other location pondered by their level of separation, which is squared to reflect the friction of distance.
• The potential model is an index of the intensity of possible interaction between social or economic groups at different locations.
• The potential model, which considers one or more interaction terms for a physical system, is used in various frameworks to investigate particle and high energy systems.
• This includes the application in ordinary wave equations of quantum mechanics to their different generalizations.

The main difference between the two models is Gravity model deals with only two places at a time, while the Potential model accounts for interactions between many places.

• Maharashtra is 45.23 percent urbanized as per 2011 census.
• Tamil Nadu is 48.45 percent urbanized as per 2011 census.
• Gujarat is 42.58 percent urbanized as per 2011 census.

Growth of Population

• Growth of population is the change in the number of people living in a particular area between two points of time. Its rate is expressed in percentage. Natural change and net migration represents the population growth rate
• Population growth has two components namely:
• Natural growth - natural growth is analysed by assessing the crude birth and death rates.
• Induced growth-induced components are explained by the volume of inward and outward movement of people in any given area.
• The rate of natural increase is the difference between the birth rate and the death rate.
• The rate of population growth is the rate of natural increase combined with the effects of migration. Thus, a high rate of natural increase can be offset by a large net out-migration, and a low rate of natural increase can be countered by a high level of net in-migration.
• The decadal and annual growth rates of population in India are both very high and steadily increasing over time.
• The annual growth rate of India’s population is 1.64 percent (2011).

Important PointsDelivered price and freight rate of firms:

• Freight Rate, the cost of transporting goods, is reflective of a number of factors aside from normal transportation costs.
• The main determining factors of freight rate are: mode of transportation (truck, ship, train, aircraft), weight, size, distance, points of pickup and delivery, and the actual goods being shipped
• The prime concern of all the theories of industrial location is to find the ‘optimal location’, which is economically the best and one that gives maximum profits.
• There has been a change in factors that distinguish earlier theories from contemporary reality: decrease in the importance of transport costs; increased organizational dynamism, interdependence, and variety, and the rise of corporate enterprise.

When the gradients of delivered price and freight rate of firms' production are the same, only distance from the location of firms can determine the boundary between the areas of two competing firms.

Key PointsLeast cost location theory by Weber:

• Proposed by Alfred Weber of Germany in the year 1909 in his book“Theory of the Location of Industries” (Uber den Standort der Industrien)
• His book is translated in English in 1929 and after that this concept became popular.
• He introduced two important concepts, isotim, and isodapens.

 Important Points

• Isotim: The line joining the places of equal transport cost (raw material cost or cost of delivery).
• Isodapen: The line joining the places having equal total cost. Total Cost = Raw material Cost + Delivery Cost

Isodapen:

• Isodapane is a similar term to the geographical term isotherm.
• It was introduced by Alfred Weber. It means "equal transportation cost", used in industrial and economic geography.
• It is a theoretical tool used to assist in finding the optimal location for industry.
• A series of isodapanes (points of equal transportation cost) are placed around the minimum cost point, with the curve farthest away from the minimum isodapane representing sites having the highest costs.

Hence, A. Weber initiated the concept of 'Isodapanes' in space-economy.

Key Points

 Political Geography after World War II:

• After the end of World War II, the Cold War and the shoring up of military-political blocs required a theoretical and ideological justification and applied studies, and therefore stimulated geopolitical works.
• The success of the state in the competition for access to natural resources and foreign markets was considered a condition necessary to raise the standard of living and to maintain social stability.
• Usually, social scientists believed that international relations were an arena of the irreconcilable struggle between nation-states for their vital interests, while they did not see deep contradictions in domestic policy.
• Nations were considered to be groups of people united by origin (“blood” kinship), historical past, language, and culture, and existing since time immemorial.
• According to this approach, each person belongs to an ethnic group since birth; members of this group are related by mutual engagements and have to fulfill specific functions within it determined by their rank in the social hierarchy.
• In other words, primordial views dominated both academic communities and public opinion.

Therefore, it can be said that, with the outbreak of World War 2, the interest in political geography was focused on Immediate problems of international relations.

• Rural house is an index of the environment because a rural house is an indication of the region’s geology, soil and vegetation.
• A rural house expresses the climate through the slope of the roof and the materials used. The availability of materials depends on the type of climate and soil.
• According to the Census of India, rural areas are defined in terms of revenue villages forming a much smaller unit of habitation than urban areas – which are under various district administrations and have surveyed boundaries which are definite.
• Each village is a separate administrative unit and can also be composed of a group of habitations together forming a unit.

Activities that generate income are termed economic activities. On the basis of economic activities, the Indian economy can be divided into 3 major sectors that are the primary sector, the secondary sector, and the tertiary sector. There are two other sectors also, called quaternary and quinary activity.

• The primary sector is in which industries are engaged in the production or extraction of natural resources such as crops, oil, and ores, etc.
• The secondary sector of the economy produces finished goods from the raw materials extracted by the primary economy.
• The tertiary sector of the economy is also known as the service industry. This sector sells the goods produced by the secondary sector.

From the above table, it can be clearly understand that coal mining is a primary activity. Handicraft, car manufacturing, etc. are related to the transformation of raw materials into goods. So, these are secondary activities. Teaching means providing services that come under the service sector of the economy.

Central Place Theory:

• The theory was postulated by Walther Christaller
• It was published in his book “Central Place in Southern Germany” (Die zentralen Orte in Suddeutschland) in 1933 and translated in English in 1966.
• It is a normative theory
• Based on the data obtained from Bavaria in South Germany
• No of settlements are represented by ‘K’

Key Points

Principles of Central Place Theory: 

Hence, transport principles are correct for the organization of settlements based on K = 4 presented in Christaller's central place model.

Key Points

Cost-input graph of industrial production system:

• In a cast input graph of industrial production, profit is maximized at the point at which an additional increment to output leaves profit unchanged.
• The point at which marginal revenue equals marginal cost maximizes a company's profit.
• The marginal cost of production measures the change in total cost of a good that arises from producing one additional unit of that good.
• The marginal revenue is calculated by dividing the change in the total revenue by the change in the quantity.
• From those input quantities and the price of inputs, the firm can determine the Total Cost of producing any level of output.
• Total cost (TC) is the price of the inputs multiplied by the quantity of the inputs.

Hence, Marginal cost equals marginal revenue is correct for the cost-input graph of the industrial production system, where the point of profit-maximizing output.

Bid-Rent Theory:

• In 1960 William Alonso completed his dissertation which extended the von Thünen model to urban land uses.
• His model gives land use, rent, the intensity of land use, population, and employment as a function of distance to the CBD of the city as a solution of an economic equilibrium for the market for space.
• The von Thünen model required considerable modification to apply to residential, commercial, and industrial land use.
• In the von thünen model, the bid-rent function declined as a result of the increased transportation costs to transport the produce of one unit of land one additional unit of distance.

Important Points

• A preliminary rationalization of a bid-rent function for a household came out of the Chicago Transportation Study.
• There the results indicated that households behaved as though they had a combined rent and transportation budget such that if transportation costs were higher then the amount that they would pay for rent is lower.
• A more sophisticated formulation assumes that households have preferences given by a set of indifference curves.
• The bid-rent function is the amount that a household could pay for rent at different locations (with differing transportation costs) such that the same level of satisfaction is achieved; i.e., the household is on the same indifference curve.
• This formulation allows for the possibility that different amounts of housing space could be chosen at different locations.
• Also, it allows for the possibility that higher-income households end up locating in the suburbs because of the relative cost of open land space there compared with locations closer the CBD.
• The bid-rent function would not have to be a straight line.
• A shift to a higher bid-rent function for a household involves the acceptance of a lower indifference curve.
• This could happen if a household found there was no location where its bid-rent function equaled or surpassed the market rent.
• Bid-rent function theory may be formulated mathematically.

Key PointsThree concepts are at the core of the land rent theory:

Rent:

• A surplus (profit) resulting from some advantages such as capitalization and accessibility.
• It is based on the capability to pay and a function of economic activity.
• The rent is usually the highest for retail because this activity is closely dependent upon accessibility to generate income.

Rent gradient:

• A representation of the decline in rent with distance from a point of reference, usually the central business district.
• This gradient is related to the marginal cost of distance for each activity, which is how distance influences its bidding rent.
• The friction of distance has an important impact on the rent gradient because with no friction all locations would be perfect locations.

Bid rent curve function:

• The combination of land prices and distances among which the individual (or firm) is indifferent.
• It describes the price range that a household (or firm) would be willing to pay at various locations in order to achieve a given level of satisfaction (utility/ profits).
• The activity that has the highest bid rent is theoretically the activity that will occupy this location.

In the above diagram, the commercial area has the highest gradient of its economic rent at 2 km distance.

Key Points

 Assertion (A) :  Most transportation networks begin as branching networks.

• A Transport network or transportation network refers to an integrated pattern in which routes of a group of centres also known as nodes (place of offloading and offloading of goods) are linked by routes.
• A transport network is an overall system consisting of transport routes and modes.
• Networks are connected through roads and streets, railways, pipes, aqueducts, and power lines.
• The branching networks are most preferred by the builders.
• Such a pattern provides the shortest route connecting all the nodes, while at the same time allowing all journeys to bypass intervening nodes.

Hence, the assertion is correct.

Reason (R): Because the first priority of the transport agencies that build them is generally to get all points connected.

• The specific purpose of transportation is to fulfill a demand for mobility since transportation can only exist if it moves passengers, freight, and information around.
• Good transport links can encourage businesses to locate nearer to one another and bring them closer to their supply chain and share expertise.
• The increase in the concentration of business economies helps improve performance and increases productivity.
• For this reason transport agencies more emphasis on making the branches of the network get connected with every point.

Hence, the reason is also correct but not a reason for the assertion.

Therefore, Both (A) and (R) are true, but (R) is not the correct explanation of (A).

The word "culture" derives from a French term, which in turn derives from the Latin "colere," which means to tend to the earth and grow, or cultivation and nurture.

Culture is the characteristics and knowledge of a particular group of people, encompassing language, religion, cuisine, social habits, music and arts.

"Culture encompasses religion, food, what we wear, how we wear it, our language, marriage, music, what we believe is right or wrong, how we sit at the table, how we greet visitors, how we behave with loved ones, and a million other things,"

• Cultural ecology is a theoretical approach that attempts to explain similarities and differences in culture in relation to the environment. Cultural ecology is the study of the adaptation of a culture to a specific environment and how changes in that environment lead to changes in that specific culture.
• It also focuses on how the overall environment, natural resources available, technology, and population density affect the rest of the culture and how a traditional system of beliefs and behavior allows people to adapt to their environment.
• Cultural convergence is the theory that two cultures will be more and more like each other as their interactions increase. Basically, the more that cultures interact, the more that their values, ideologies, behaviors, arts, and customs will start to reflect each other.
• Cultural diffusion describes the spread of one culture’s practices, beliefs, and/or items, like food, music, or tools. This spread can be among members of the same culture or to completely different cultures around the world. Cultural diffusion is why many cultures around the world share similarities.
• A cultural hearth is a nuclear area within which an advanced and distinctive set of culture traits, ideas and technologies develops and from which there is diffusion of those characteristics and complexes.

• As per Census 2011, the Maximum ratio of ST are in the following states:-
• Mizoram - 94.8 Percent
• Nagaland - 86.5 %
• Meghalaya - 86.1 %
• Arunachal Pradesh - 68. 8 %
• Lakshadweep is the Union territory in which the ST Population is 94.8 % and it the highest in UTs.
• ST is 8.6 per cent of the total population of India according to census 2011.
• The decadal growth rate of the scheduled tribes was 23.7 per cent during the period 2001-2011.

Important Points

Network topology:

• Graphs have some properties that are very useful when unraveling the information that they contain.
• It is important to realize that the purpose of any type of network analysis is to work with the complexity of the network to extract meaningful information that you would not have if the individual components were examined separately.
• Network properties, and particularly topological properties, can help us identify relevant sub-structures within a network.
• Topology is the way in which the nodes and edges are arranged within a network.
• Topological properties can apply to the network as a whole or to individual nodes and edges.

Key Points

1. Nodes: The nodes represent different entities (e.g. proteins or genes in biological networks)
2. Edges: The edges convey information about the links between the nodes.
3. Diameters: The diameter of a graph is the maximum eccentricity of any vertex in the graph. That is, it is the greatest distance between any pair of vertices. The diameter of a network is defined as the longest path of the shortest path between any two nodes. For example, the diameter of a 4x4 mesh D = 6

Given,  Vertices 6, Edges 6, Diameter 4

Comparison:

Hence, only the first image is true as per the given data in the question.

In respect of matters on which both the Parliament and the state legislatures have the power of legislation (i.e., the subjects enumerated in the Concurrent List), the executive power rests with the states except when a Constitutional provision or a parliamentary law specifically confers it on the Centre.

Constitution confers executive power of a subject in the Concurrent List to the State Government.

Union List:

• The Union List is a list of 100 (Originally 97) numbered items as provided in the Seventh Schedule to the Constitution of India. The Union Government or the Parliament of India has exclusive power to legislate on matters relating to these items.
• Post and Telegraph, Defence and Banking

State List:

• The State List is a list of 61 (Originally 66) items in the Schedule Seven to the Constitution of India.  The respective state governments have exclusive power to legislate on matters relating to these items.

Concurrent List:

• There are 52 (Originally 47) items currently on the list: This includes items that are under the joint domain of the Union as well as the respective States. However, given that there can be conflict when it comes to laws passed by Parliament and state legislatures on the same subject, the Constitution provides for a central law to override state law.
• Price Control comes under Concurrent List.

• The monumental Politische Geographie (1897) is described as the 1st book on modern political geography by Friedrich Ratzel that is based on the organismic analogy, following which the concept of Lebensraum gained popularity.
• The concept of Lebensraum states that all living organisms are involved in an endless struggle for space and the most powerful will have the largest space.

• The word geopolitics was originally coined by the Swedish political scientist Rudolf Kjellén about the turn of the 20th century, and its use spread throughout Europe in the period between World Wars I and II (1918–39) and came into worldwide use during the latter.
• Geopolitics is a framework that we can use to understand the complex world around us. Global politics, or “getting what you want in the world” involves thinking and acting geographically.
• Geopolitics explains how countries, businesses, terrorist groups, etc. try to reach their political goals by controlling geographic features of the world. We call these features geographical entities.
• Geographical entities are the places, regions, territories, scales, and networks that make up the world. Geopolitics looks at a particular use of power: how countries and other groups compete to control these entities within the international community. Controlling these entities is seen to help countries and groups reach their goals.
• Geopolitics is always looked at with an international and global dimension, meaning that the issues being looked at are connected to the global scale. Thus, geopolitics can be defined as the struggle over the control of geographical entities with an international and global dimension, and the use of such geographical entities for political advantage.

Culture is the specialized behavioral social patterns, understandings, adaptations, and social systems that summarize a group of people’s learned way of life.

Key Points

Hence, the correct sequence in decreasing order is Realm, Region, Complex, Trait

John Robert Victor Prescott is the author of the book 'The Geography of State Policies'.

John Robert Victor Prescott:

• John Robert Victor Prescott (12 May 1931 - 17 August 2018) FASSA was a British and Australian academic, author, and professor emeritus at the University of Melbourne.
• A political geographer, most of Prescott's work focused on international boundary issues, particularly maritime boundaries.
• He was interested in political geography, specifically focusses on borders and frontiers.
• His other studies included Australian Aboriginal conceptions of territory and frontiers, border disputes in South East Asia and the South China Sea, and the effects of the colonial period on African borders.

The Geography of State Policies:

• This book was published in 1968.
• This book examines the reciprocal relationships between geography and the policies of states.
• The text begins with a theoretical analysis which sets the study in the context of geography and related fields, and an analysis of certain global strategies advocated by geographers and others.

Hence, J. R. V. Prescott is the correct answer here.

• The 14th finance commission recommended increase in the share of states in the centre's tax revenue from the current 32% to 42%-the single largest increase ever recommended.
• The recommendation, which the government will likely accept, will give more power to states in determining how they spend this money (it also correspondingly reduces the fiscal resources available to the centre).

Material Index was devised by Alfred Weber to indicate if the optimal location was closer to either raw material source or the market.

The Material Index is part of the least cost location principle and defined as the ratio of the weight of localised materials used in the industry to the weight of the product.

The material index equals 1 when there is no weight loss in the production, while if the material index is higher than 1, there is substantial weight loss.

• Material Index = Weight of localized materials/weight of the finished products.
• If material index > 1 then the plant would be located near the sources of materials.
• If material index < 1 then the plant would be located near to the market.

Assertion (A) : The decade of 1990s witnessed urbanisation process speeding up economic growth in India.

• The post–1991 India witnessed a rapid growth in GDP on a continual basis for two decades. The growth of GDP increased from 5.6 per cent during 1980–91 to 8.2 per cent during 2007–12.
• It was the year when Economic reforms were introduced in the year 1991 in India to combat the economic crisis.
• The Government of India announced the New Economic Policy(NEP) in 1991
• It was in this time period we witnessed urbanisation process speeding up economic growth in India.

Reason (R) : The urbanisation process resulted in a growing shortage of urban services and an overall deterioration in the quality-of-urban-life indices.

• The process of urbanisation affects all sizes of settlements, villages gradually grow to become small towns, smaller towns become larger towns, and large towns become cities. This trend has led to the growth of mega-cities. A mega-city is an urban area of greater than ten million people. Rapid expansion of city borders, driven by increases in population and infrastructure development, leads to the expansion of city borders that spread out and swallow up neighbouring urban areas to form mega-cities. These things resulted into growing shortage of urban services and an overall deterioration in the quality-of-urban-life indices
• However it is not the cause of speeding up of urbanization process and economic growth in India in 1990s.

Key Points 

Hence, the correct matching is (a) - 4, (b) - 3, (c) - 2, (d) - 1

Important Points

Regional classification by The town and country planning organization:

• The town and country planning organization suggested a scheme of planning region delineated on the principle of economic viability, self-sufficiency, and ecological balance at the macro and meso levels.
• The emphasis of the scheme was to introduce regional factors in economic development.
• The approach was aimed to complement the macro planning at the national level, with a component of regional policies, aimed at reducing regional disparities in the development.
• The macro regionalization sought to link a set of areas, rich in one type of resources with areas having complementary resources or even resource-poor areas, so that the benefits of economic activity in the former may flow into the latter.
• The scheme proposed 13 macro-regions which are further divided into 35 meso regions and 3 metropolitan areas

Cantonment Towns

• The nature of the colonial city changed further in the mid-nineteenth century. After the Revolt of 1857 British attitudes in India were shaped by a constant fear of rebellion. They felt that towns needed to be better defended, and white people had to live in more secure and segregated enclaves, away from the threat of the “natives ”.
• Pasturelands and agricultural fields around the older towns were cleared, and new urban spaces called “Civil Lines” were set up. White people began to live in the Civil Lines.
• Cantonments– places where Indian troops under European command were stationed – were also developed as safe enclaves. These areas were separate from but attached to the Indian towns. With broad streets, bungalows set amidst large gardens, barracks, parade ground and church, they were meant as a safe haven for Europeans as well as a model of ordered urban life in contrast to the densely built up Indian towns.

Railway Colonies

• The introduction of railways in 1853 meant a change in the fortunes of towns. Economic activity gradually shifted away from traditional towns which were located along old routes and rivers. Every railway station became a collection depot for raw materials and a distribution point for imported goods.
• With the expansion of the railway network, railway workshops and railway colonies were established. Railway towns like Jamalpur, Waltair and Bareilly developed.

Hill Stations

• As in the case of cantonments, hill stations were a distinctive feature of colonial urban development. The founding and settling of hill stations was initially connected with the needs of the British army.
• Simla (present-day Shimla) was founded during the course of the Gurkha War (1815-16); the Anglo-Maratha War of 1818 led to British interest in Mount Abu; and Darjeeling was wrested from the rulers of Sikkim in 1835.
• Hill stations became strategic places for billeting troops, guarding frontiers and launching campaigns against enemy rulers.

Key Points

Assertion (A):  The city plans in ancient India were laid down in accordance with some preconceived ideas, with high standards of public health.

• Hygiene is a very important part of life as it keeps each one of us healthy both physically and mentally.
• Some people have a tendency to believe that modern man knows best and that our ancestors were unaware of the hygiene practices.
• Ancient Indians took very much care to care for their skin, cleanliness, and hygiene has been imbibed into the Indian culture since the Harappa and Mohenjo-Daro times.
• Cleanliness is equally important when it comes to food and its preparation.
• One of the ancient civilizations of the world is Indus Valley Civilization in India.
• The drainage system was one of the most remarkable features of Harappan city.

Hence, the assertion is correct.

Reason (R): This does not, however, reflect the concern of ancient India for community sanitation and health.

• The overall purpose of the hygiene and sanitation program is to improve hygiene behaviors and encouraging effective community management of sanitation and water sources to reduce diseases.
• Improved sanitation leads to lower disease burden, improved nutrition, reduced stunting, improved quality of life, increased attendance of girls at school, healthier living environments, better environmental stewardship, increased job opportunities and wages, improved competitiveness of cities, and economic and social environment.

Hence, that reason is incorrect.

Therefore, (A) is true, but (R) is false.

P. Sengupta along with Galina Sdasyuk (1968) presented a three-tier classification of India's agricultural regions in the 'Economic Regionalization of India'.

• (i) Climatic characteristics : 4 macro regions.
• ii) Physiographic characteristics: 11 meso regions.
• (iii) Crop combinations : 60 micro region

• The Scheduled Tribe (ST) population of Jharkhand State is as per 2001 census constituting 26.3 per cent of the total population (26,945,829) of the State.
• Among all Sates and UTs, Jharkhand holds 6th and 10th ranks terms of the ST population and the percentage share of the ST population to the total population of the State respectively.
• The state has a total of thirty (30) Scheduled Tribes and all of them have been enumerated at 2001 census
• Out of thirty (30) Scheduled Tribes notified for the State, Santhal is the most populous tribe constituting 34 per cent of the total ST population of the State.
• The total population of West Bengal at 2001 Census has been 80,176,197.
• Scheduled Tribes (STs) constituting 5.5 per cent of the total population of the state. There are total thirty eight (38) notified STs in the state. The Santal represents more than half of the total ST population of the state.
• Hence, Jharkhand, Odisha, West Bengal States recorded Santhal tribe population as per census of India, 2011

Key Points

• The Peninsular plateau is a tableland composed of the old crystalline, igneous and metamorphic rocks.
• It was formed due to the breaking and drifting of the Gondwana land and thus, making it a part of the oldest landmass.
• The plateau has broad and shallow valleys and rounded hills.
• This plateau consists of two broad divisions, namely, the Central Highlands and the Deccan Plateau.
• The part of the Peninsular plateau lying to the north of the Narmada river, covering a major area of the Malwa plateau, is known as the Central Highlands.
• The Vindhyan range is bounded by the Satpura range on the south and the Aravalis on the northwest. The further westward extension gradually merges with the sandy and rocky desert of Rajasthan. The flow of the rivers draining this region, namely the Chambal, the Sind, the Betwa, and the Ken is from southwest to northeast, thus indicating the slope.
• The Central Highlands are wider in the west but narrower in the east. The eastward extensions of this plateau are locally known as the Bundelkhand and Baghelkhand.

Important PointsCentral highland is broadly classified into four plateaus namely

1. Malwa plateau
2. Bundelkhand plateau
3. Bhagelkhand plateau
4. Chotanagpur plateau.

Hence, the Malwa plateau is a part of the central highland and not comes under the southern part of it. Maharastra plateau is located in the western part, Chota Nagpur in the eastern part, and Vindhya is located in the southern portion of it.

Chorochromatic technique is best suited to show delineated areas having different colours.

• It is also applicable in indicating political, cultural, ethnological distinctions between places usually made by shading each unit areas
• Chorochromatic techniques imply the drawing of boundary lines to delimit specific areas within which shading or coloring is applied to mark distinctive features
• Chorochromatic maps can be simple or compound
• In simple chorochromatic maps, single features with patchy occurrence are depicted (e.g. distribution of forest resources or mining fields in a country)
• Compound Chorochromatic maps show phenomena in which types and categories can be recognized.

Isopleth

• Data are represented on some maps by lines each of which is inconsistent esteem. Accordingly, a line which joins places of equivalent value in regard to some distribution is generally called as ISOPLETH. It is a combination of Greek words ISOS-(means same) and Plethron-(means measure). Thus a line on a map joining points having the same amount of rainfall is an isopleth and is called as ISOHYET.
• Similarly, an isopleth connecting places of equal temperature is called an Isotherm, Isobars for equal pressure, Isobath for equal depth, Isohaline for equal salinity etc.

Choropleth

• It is employed to represent the variations in the distribution of average value per unit area within the geographical or administrative divisions by applying various cartographic shades.
  

It is a system of depicting the variations with the assistance of various shades or outlines which demonstrate very low, low, medium, high and very high estimations of the distribution of data. It is used to show various demographic features like the density of population, age-structure, sex-ratio, literacy levels etc.

Choroschematic

• ​In this technique, the geographical phenomenon like soil, land use, vegetation etc. are depicted by various cartographic symbols like dots, circles, triangles, initial letters of the elements to represent on the map. This method mostly stresses on the location rather than the characteristics of the phenomenon. Neither the shape nor the color of the symbol used represents the dimension of the object. The main advantage of this method is that many elements may be shown together on a single map.

Third Five Year Plan

• The Third Five Year Plan has been the dawn of the regional development and had become a distinct policy of the government. This plan for the first time made a specific provision of around 30 million rupees for the preparation of comprehensive development plans for urban and regional development.
• This also gave a strong impetus to the development of cities, towns, regions as well as planning for river valley regions and industrial regions.
• In the Third Plan it will be essential to link up the programme more closely with different schemes of community development such as provision of water supply, roads, drainage, public health, education etc.
• It is also necessary that rural housing activities should be effectively coordinated with other connected programmes of rural development so as to ensure that the villages selected under the village housing scheme derive the maximum benefit from the limited resources which are available.
• The Third Plan provides for a programme of about Rs. 29 crores for slum clearance and improvement

Key Points Characteristics of Development: 

• Development is Interrelated: Growth and development always go hand in hand (in general) but development is also possible without growth as some people do not gain in size but do experience functional improvement or development in social, intellectual, or social aspects. This concept is known as the Principle of Interrelation. This Development always stands for Growth with change.
• Development is Lifelong: This belief has two separate aspects. First, the potential for development extends across the entire life span: there is no assumption that the life course must reach a plateau or decline during adulthood and old age. Second, development may involve processes that are not present at birth but emerge throughout the life span.
• Development is Multidimensional: Multidimensionality refers to the fact that development cannot be described by a single criterion such as increases or decreases in a behavior. It occurs in the biological, cognitive, and social-emotional domains.
• Development is affected by cultural changes: An individual’s development is molded to conform to cultural standards and norms, while changes in these standards affect the developmental pattern.
• Development is Contextual: Development varies across the different contexts in which we live our lives. For example, social and rural environments are associated with different sets of factors that have the potential to impact development; understanding how development differs for individuals within these two settings requires an understanding of the differing contexts. It occurs in the context of a person’s biological makeup, the physical environment, and social, historical, and cultural contexts.
• Development is Multidirectional: The principle of multidirectional maintains that there is no single, normal path that development must or should take. In other words, healthy developmental outcomes are achieved in a wide variety of ways. Development is often comprised of multiple abilities that take different directions, showing different types of change or constancy.

Hence, from the above-mentioned characteristics of Development**, one could easily conclude that Development stands for growth with change.**

River narmada does not form a delta.

River Narmada:

• The Narmada is the westward flowing river of Peninsular India.
• Source: The Narmada rises from the western flank of Amarkantak plateau in the state of Madhya Pradesh.
• Mouth: The Narmada river drains into the Gulf of Khambat (the Arabian Sea) near Bharuch in the state of Gujarat.
• The river flows in a rift valley between the Vindhyas in the north and the Satpura in the south.
• The river forms a picturesque gorge in marble rocks.
• The Narmada forms the Dhaundhar waterfalls, southwest of Jabalpur.
• It forms the traditional boundary between North India and South India.
• Peninsular rivers, such as the Narmada and the Tapi form estuaries.

Most of the major rivers of the peninsula such as the Mahanadi, the Godavari, the Krishna and the Cauvery flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths. Hence, only Narmada from th elist does not form delta.

• Stratified sampling method is appropriate when the population has mixed characteristics, and you want to ensure that every characteristic is proportionally represented in the sample.
• You divide the population into subgroups (called strata) based on the relevant characteristic (e.g. gender, age range, income bracket, job role).
• Stratification divides all cases into groups, based on one or more variables, for the computation of expected values. The Empirica Signal application sums these expected values across all of the strata to provide a single expected value for all of the cases in the background.
• Here according to the question, the Stratified variable is the correct option as in this variable the target population or in this case the universe of 500 students is divided into 2 stratums on the basis of homogenous characteristics and then from each of those sub-groups a simple random sample is collected. Hence, the correct option is 4th.

Integrated Development of Small and Medium Towns (IDMST)

• The Centrally-sponsored Scheme of Integrated Development of Small and Medium Towns (IDSMT) was initiated in the Sixth Plan (1979-80) and has continued in the Seventh and Eighth Plans.
• Its main objective has been to slow down migration from rural areas end smaller towns to large cities by the development of selected small and medium towns which are capable of generating economic growth and employment.
• Generally migration takes place from villages and towns to cities in search of employment and income opportunities. “Poverty-push” and “prosperity-pull” factors coupled with the expectations that cities offer diverse opportunities for jobs and better living conditions are primarily responsible for this.
• The IDSMT Scheme; by strengthening small and medium towns as regional growth centres aims at reducing migration to large and metropolitan cities. Through the establishment of complementary, linkages between villages, towns and cities, it envisages a harmonious pattern of settlements.

The Objectives of the IDSMT Scheme are :

• Improving infrastructural facilities and helping in the creation of durable public assets in small and medium towns having potential to emerge as regional centres of economic growth and employment, thereby reducing the incentives for people belonging lo rural and smaller urban areas to migrate to bigger cities and towns for jobs.
• Decentralising economic growth and employment opportunities and promoting dispersed urbanisation while taking due advantage of the functional interlinkages between villages, towns and cities through a regional planning approach.
• Increasing the availability of serviced sites for housing, commercial and industrial uses and promoting the principles of planned and orderly spatial development.
• Integrating spatial and socio-economic planning as envisaged in the Constitution (74th Amendment),1992 and preparing and implementing Town/City Development Plans.
• Promoting resource-generating schemes for the urban local bodies to improve their overall financial position and ability to undertake long-term infrastructure development programmes on their own as well, as to repay the borrowed capital and usher in necessary municipal reforms.

• The National Capital Region (NCR) Planning Board came into being by virtue of the NCR Planning Board Act, 1985 passed by Parliament and duly confirmed by the legislatures of Haryana, Rajasthan and Uttar Pradesh.
• The preamble of the said Act stipulates: “An Act to provide for the constitution of a Planning Board for the preparation of a plan for the development of the National Capital Region and for coordinating and monitoring the implementation of such plan...” The total area of the National Capital Region is 33,578 sq. kms. excluding the area of Counter Magnet Areas (CMAs).
• The National Capital Territory of Delhi: is less than 4.5% of the NCR.
• The major objective behind identification of five counter-magnet cities outside the National Capital Region (NCR) was to further strengthen policies for decentralisation of economic activities within and outside the NCR. And to further strengthen policies for decentralisation of population within and outside the NCR.
• The basic objectives of the NCR regional plan and this was to be accomplished through checks on the location of large industries in Delhi and encourage the dispersal of industries and other job opportunities elsewhere in the NCR.
• There was also a suggestion to decentralise the selected government offices by developing the transport network, water supply, power supply, housing, medical and educational facilities.

The administrative units of the National Capital Region are:

• Union Territory of Delhi;
• Uttar Pradesh Sub-Region comprises  Meerut, Ghaziabad, Gautam Bhudha Nagar, Bulandshahr and Baghpat districts;
• Rajasthan Sub-Region comprises  the Alwar district; and
• Haryana Sub-Region comprises  Faridabad, Gurgaon, Mewat, Rohtak, Sonepat, Rewari, Jhajjar and Panipat districts.

Key PointsThe coastline of India:

• The peninsular part of India extends towards the Indian Ocean.
• This has provided the country with a coastline of 6,100 km on the mainland
• The total length of the coastline of the mainland, Lakshadweep Islands, and Andaman & Nicobar Islands are 7,516.6 km.
• India's coastline extends to Nine states (Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal) and four Union Territories (Puducherry, Lakshadweep, Daman & Diu, and Andaman & Nicobar Islands).
• Gujarat has the largest share (23%) in India’s coastline, followed by Andhra Pradesh and Tamil Nadu.

Hence, the Indian coastline extends up to 9 states, i.e. Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal and its total length is 7,516.6 km.

Data collecting, storing, retrieving, transforming and displaying spatial data from the real world are the main task for the computer in mapping the geographical data. Technology that provides the means to collect and use geographic data to assist in the development work is known as Geographical Information System (GIS).

• A geographic information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth’s surface. By relating seemingly unrelated data, GIS can help individuals and organizations better understand spatial patterns and relationships.
• GIS technology is a crucial part of spatial data infrastructure, which the White House defines as “the technology, policies, standards, human resources, and related activities necessary to acquire, process, distribute, use, maintain, and preserve spatial data.”
• GIS can use any information that includes location. The location can be expressed in many different ways, such as latitude and longitude, address, or ZIP code.
• Many different types of information can be compared and contrasted using GIS. The system can include data about people, such as population, income, or education level. It can include information about the landscape, such as the location of streams, different kinds of vegetation, and different kinds of soil. It can include information about the sites of factories, farms, and schools, or storm drains, roads, and electric power lines.
• With GIS technology, people can compare the locations of different things in order to discover how they relate to each other. For example, using GIS, a single map could include sites that produce pollution, such as factories, and sites that are sensitive to pollution, such as wetlands and rivers. Such a map would help people determine where water supplies are most at risk.

The percentage of decadal growth of population during 2001-2011 as per Census 2011 is 17.64.

Decadal Growth Rate of Different Indian States are:

Additional Information

Decadal growth of population in the recent census:

• As per Census 2011, the country’s Decadal Growth Rate was 17.7%.
• India’s population in 2011 is estimated to be 1.21 billion, comprising 624 million males and 587 million females.
• While the gender imbalance in the population remains, the preliminary census figures show that India’s female population grew by 18.12 per cent over the past decade against 17.19 per cent for males.
• India’s population accounts for the world’s 17.5 per cent, second only to China that constitutes 19.4 per cent.
• The country’s headcount is almost equal to the combined population of the United States, Indonesia, Brazil, Pakistan, Bangladesh and Japan, put together.
• The population of India has increased by more than 181 million during 2001-11.
• Uttar Pradesh is the most populous state with 199 million people and Lakshadweep the least populated at 64,429.

• Remote sensing is the acquiring of information from a distance. Remote sensors, which provide a global perspective and a wealth of data about Earth systems, enable data-informed decision making based on the current and future state of our planet.
• With the development of remote sensing from space, satellite data offers the possibility for measuring land surface temperature over the entire globe with sufficiently high temporal resolution and with complete spatially averaged rather than point values.
• It is also possible to measure chlorophyll content in the vegetation of a specific location as chlorophyll will reflect more light in the green and near infrared spectrum compared to other wavelengths.
• Remote sensing from satellites can also deliver information on green house gas(GHGs) soil emissions by estimating tropospherical, near-surface CO2 and CH4 concentrations based on the measurement of the intensity of the reflected sunlight in small wavelength bands in the visible and short-wavelength IR portion of the spectrum.
• Remote sensing has emerged as a major tool in studying and analyzing the complex water resource systems.
• However, whilst the efficiency of the response can be hampered when cloud cover limits image availability.

• Coimbatore is among the most industrially developed and commercially vibrant districts in Tamil Nadu.
• The region’s industrial economy is largely driven by textiles, textile machinery, auto components, steel and aluminium foundries, pumps and motors, gold and diamond jewellery, educational institutions and information technology (IT).
• Once hailed as the ‘Manchester of the South’, Coimbatore houses a large number of small and medium textile mills.
• The term “Coimbatore Wet Grinder” was given a Geographical indication for wet grinders manufactured in Coimbatore and Erode. Coimbatore is home to a common facility for the manufacturers of wet grinders. Pump manufacturing, It is also called as the Pump City of India. The city also houses numerous jewellers engaged in jewellery exports. Major Wind Energy Company’s are located in and around Coimbatore.
• Kolkata is the centre of India’s large jute-processing industry. The jute industry was established in the 1870s, and mills now extend north and south of the city centre on both banks of the Hugli River.
• Engineering constitutes the city’s other major industry. In addition, city factories produce and distribute a variety of consumer goods—notably foodstuffs, beverages, tobacco, and textiles—other light manufactures, and chemicals.
• Mumbai, with cotton hinterland and moist climate favoured the location of cotton textile industry. Hydro-electricity was developed in the Western Ghats region to meet the requirements of this industry. With the development of cotton textile industry, chemical industry also developed.
• Important industrial centres are Mumbai, Kolaba, Kalyan, Thane, Trombay, Pune, Pimpri, Nashik, Manmad, Solapur, Kolhapur, Ahmednagar, Satara and Sangli.

Important Points Linear regression analysis:

• Linear regression analysis is used to predict the value of a variable based on the value of another variable.
• The variable you want to predict is called the dependent variable.
• The variable you are using to predict the other variable's value is called the independent variable.
• This form of analysis estimates the coefficients of the linear equation, involving one or more independent variables that best predict the value of the dependent variable.
• Linear regression fits a straight line or surface that minimizes the discrepancies between predicted and actual output values.
• There are simple linear regression calculators that use a “least squares” method to discover the best-fit line for a set of paired data.
• You then estimate the value of X (dependent variable) from Y (independent variable).

Shortcut Trick

 $\overline X = 5.50$, 

$\overline Y = 3.50$ 

b = 1.50 

(Y = a + bX)

Putting the values in the equation, 

3.50 = a + (1.50*5.50)

or, 3.50 = a + 8.25

or, a = -4.75

Hence, the value of 'a' of the model is -4.75

Key Points

Assertion (A):  Nearest neighbor analysis is an approach to the study of point, line, and area partners.

Nearest neighbor statistic: 

• Nearest Neighbor Analysis measures the spread or distribution of something over geographical space.
• It provides a numerical value that describes the extent to which a set of points are clustered or uniformly spaced.
• This command uses the Clark and Evans (1954) aggregation index R as the basis for a crude test of clustering or order of a point pattern with the help of point, line, and area.

Hence, the assertion is correct.

Reason (R): Measurement of distance by comparing the observed mean distances with the expected mean distances between sampled points and their nearest neighbors.

• The Rn value determines the randomness of the given settlements.
• For this two things are requires, Area (a) and the length between settlements.
• The formula is, $\rm Rn = \dfrac{\bar{D}(Obs)}{0.5 \sqrt{\dfrac{a}{n}}}$
• Where, a = total area, n  = number of settlement, D = mean distance

Hence, the reason is also correct.

Important Points

Analysis of the question:

Therefore, both (A) and (R) are true and (R) is the correct explanation of (A).

The pie diagram represents the occupational structure of the population.

Pie diagram:

• Pie diagrams are useful for showing a particular amount in relation to the whole as:

• pie slices are proportional to the fraction of the whole in each category.

• pie slices are used to illustrate relative sizes of data or numerical proportions.

• pie slices are helpful to show a comparison between the most and least popular items.

• pie slices accurately showing how each item of data contributes to the complete picture.

• It could be concluded that pie diagrams are useful for showing a particular amount in relation to the whole.

• For example, the diagram below showing various occupations of people of aregion.

• Isopleth: Isopleth maps simplify information about a region by showing areas with continuous distribution.

• Contour: A Contour line is an imaginary outline of the terrain obtained by joining its points of equal elevation

• Choropleth: Choropleth maps are popular thematic maps used to represent statistical data through various shading patterns or symbols on predetermined geographic areas (i.e. countries).

Terrain elevation could be correctly represented in a contour map.

Contour:

Line joining points of the same elevation are called contour lines.

Contour Interval:

• The elevation difference between two consecutive contours is called contour interval.
• It is always kept the same or constant for a map.

Horizontal equivalent:

The horizontal distance between two consecutive contours is called equivalent.

Important Points

• If contours are parallel and spacing between them is also constant then it shows a uniform slope.

• Closely spaced contour represents a steep slope and distant contours represent generally mild slope.

• Closed contours (loop) represent either a hill or a pond.

• For a hill, readings increase toward the center and for a pond, it decreases toward the center.

• Ridgeline/valley line intersect contour at a right angle. (Line joining topmost point of a hill is called Ridgeline and the line joining bottom-most points of a valley is called Valley line.)

• Two contours of different elevation neither touch nor cross each other. (Exception: Vertical cliff & Overhanging cliff)

​

Hence, population distribution, rock hardness, or soil distribution are not shown using contour, it is suitable for terrain elevation and slope.

Isochrone map denotes the lines joining an equal amount of travel time.

Key PointsIsochrone:

• An isochrone (iso = equal, chrone = time) is defined as "a line drawn on a map connecting points at which something occurs or arrives at the same time".
• Early examples of Isochrone maps include the Galton´s Isochronic Postal Charts and Isochronic Passage Charts of 1881 and 1882
• An isochrone shows points of an equal value joined together.
• It's most commonly used to depict travel times, such as drawing a 30 minute travel time perimeter around a start location.
• The isochrone below joins up all points within a 45-minute drive from the origin.
• It is a type of Isarithmic map.
• An Isarithmic map is a type of Thematic map that represents a continuous field using line and/or region symbols to connect places of similar value.

Additional Information

• Isohaline: Isohalines are lines (or contours) that join points of equal salinity in an aquatic system.
• Isoheight: An isoheight or isohypse is a line of constant geopotential height on a constant pressure surface chart.
• Isopleth: Isopleth maps simplify information about a region by showing areas with continuous distribution.

Simple random sampling techniques become more appropriate for homogeneous population groups.

Sampling is a statistical procedure that is concerned with the selection of certain individual observations from the target population. It helps to make statistical inferences about the population.

There are two types of sampling

1. Probability sampling
2. Nonprobability sampling

Simple random sampling:

• Simple random sampling is a type of probability sampling.
• It is a sampling procedure where each element in the population will have an equal chance of being selected in the sample.
• This process is simple because it requires only one stage of the sample selection process.
• Here we number each frame unit from 1 to N.
• Then use a random number table or a random number generator to select n distinct numbers between 1 and N, inclusively.
• It is easier to perform for small populations but cumbersome for large populations.

Conrad discontinuity is found between Sial and Sima.

Key Points

• The border at which the density of SIAL and SIMA changes is known as Conrad discontinuity.
• SIAL indicates the composition of Silica and Aluminium whereas SIMA indicates the composition of Silica and Magnesium.
• A boundary within the Earth's continental crust that can be detected seismically at about 10–12 km depth
• The exploratory deep drilling has failed to locate it.
• The boundary separates the crust into a lower, basic layer and an upper, granitic layer.

Important PointsSeismic Discontinuities: Seismic discontinuities aid in distinguishing divisions of the Earth into the inner core, outer core, lower mantle, upper mantle, and crust.

• Conrad discontinuity refers to the zone between the upper crust and lower crust.
• Mohorovic discontinuity also called Moho discontinuity is the zone that separates the Earth's crust from the upper mantle. It can be detected by a sharp increase downward in the speed of earthquake waves there.
• Repiti discontinuity refers to the zone between the upper mantle and lower mantle.
• Gutenberg discontinuity refers to the zone separating the lower mantle from the core. It is located at a depth of about 2,900 km.
• Lehmann discontinuity refers to the zone separating the solid inner core from the liquid outer core.

Hence, the correct matching is (a) - 2, (b) - 1, (c) - 4, (d) - 3

1. J. A Steers: James Alfred Steers was a geographer and conservationist
2. Von Ricthofen: He was a German traveler, geographer, and scientist. He is noted for coining the terms "Seidenstraße" and "Seidenstraßen" = "Silk Road(s)" or "Silk Route(s)" in 1877.
3. Wooldridge: Professor Sidney William Wooldridge was a  geologist, geomorphologist and geographer, was a pioneer in the study of the geomorphology of south-east England and the first professor of geography at King's College London.

The electromagnetic spectrum is a continuum of all electromagnetic waves arranged according to frequency and wavelength. The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, X-rays, and gamma-rays. Among these waves, Ultraviolet radiation causes human skin cancer.

Ultraviolet radiation:

• UV radiation is part of the natural energy produced by the sun.
• On the electromagnetic spectrum, UV light has shorter wavelengths than visible light, so your eyes can’t see UV, but your skin can feel it.
• Tanning beds also emit UV radiation.
• Two types of UV light are proven to contribute to the risk for skin cancer:
• Ultraviolet A (UVA) has a longer wavelength and is associated with skin aging.
• Ultraviolet B (UVB) has a shorter wavelength and is associated with skin burning.
• While UVA and UVB rays differ in how they affect the skin, they both do harm.
• Unprotected exposure to UVA and UVB damages the DNA in skin cells, producing genetic defects, or mutations, that can lead to skin cancer (as well as premature aging.)
• These rays can also cause eye damage, including cataracts and eyelid cancers.

Hence, Ultraviolet radiation is the correct answer.

Key PointsThe concept of Calory:

• Calorie, abbr. cal, a unit of heat energy in the metric system.
• The measurement of heat is called calorimetry.
• The calorie, or gram calorie, is the quantity of heat required to raise the temperature of 1 gram of pure water 1°C.
• The kilocalorie, or kilogram calorie, is the quantity of heat required to raise the temperature of 1 kg of pure water 1°C; it is equal to 1,000 cal.
• The kilocalorie is used in dietetics for stating the heat content of a food, i.e., the amount of heat energy that the food can yield as it passes through the body; in this context, the kilocalorie is usually called simply the calorie.
• The amount of heat energy needed to effect a 1°C temperature increase in 1 gram of water varies with temperature (see heat capacity); thus the temperature range over which the heating takes place must be stated to define the calorie precisely.
• The 15° calorie, or normal calorie, is widely used in chemistry and physics; it is measured by heating a 1-gram water sample from 14.5°C to 15.5°C at 1-atmosphere pressure.
• The 4° calorie, also called the small calorie or therm, is measured from 3.5°C to 4.5°C (water is most dense at 3.98°C); the large calorie, or Calorie, is equivalent to 1,000 small calories.
• The average value of the calorie in the range 0°C to 100°C is called the mean calorie; it is  1⁄100 of the energy needed to heat 1 gram of water from its melting point to its boiling point.
• The calorie may also be defined by expressing its value in some other energy units.

Hence, 10 calories is required calories of heat to increase the temperature by 10º C for 1 gram of water

As the Earth revolves around the sun throughout the year, different parts receive varying amounts of heat. The part (pole) which is more tilted towards the sun experiences longer days and a hotter climate during that period. As different parts of Earth are tilted towards the sun throughout the year while revolution, solstices, and equinoxes are experienced.

Key PointsAssertion (A): During an equinox, the length of daylight is 12 hours everywhere on the Earth.

Equinox:

• An equinox is the instant of time when the plane of Earth's equator passes through the geometric center of the Sun's disk.
• Equinox refers to a day with an equal duration of day and night.
• We have two equinoxes in a year which are:
• Spring equinox on March 20
• Autumnal equinox on September 22.
• It is the moment at which the center of the visible Sun is directly above the equator.
• In the Northern Hemisphere, the March equinox is called the vernal or spring equinox while the September equinox is called the autumnal or fall equinox.
• In the Southern Hemisphere, the reverse is true.
• The equinoxes are the only times when the edge between night and day is perpendicular to the equator.
• As a result, the northern and southern hemispheres are equally illuminated.
• This is also the time when the Sun rises for an observer at one of Earth's rotational poles and sets at the other; for a brief period, both North and South Poles are in daylight.

Hence, the assertion is correct.

Reason (R): The circle of illumination passes directly through the poles, thus dividing the lines of latitude in the middle.

Circle of illumination:

• The imaginary line which divides the parts of the earth with day and night is called the circle of illumination.
• The circle of illumination is at a right angle to the orbital plane.
• Thus, the circle of illumination is at an angle of 23.5º to the earth’s axis.
• It divided the equator into two equal halves.
• Because of the angle between the circle of illumination and the axis; both the hemispheres of the earth do not get the same amount of light on most of the days.
• This causes different seasons at different times of the year.

• The circle of illumination cuts all latitudes into half on the spring and autumnal equinoxes.
• The circle of illumination bisects the equator while the circle of illumination separates light from darkness and day from night, the axis is a line along which the earth rotates.

Hence, the reason is also correct.

Therefore, both (A) and (R) are true and (R) is the correct explanation of (A).