Mathematics and Science PYQs

The Correct answer is The lens could be moved either away or toward the wall depending on its position.

Explanation:

• A student attempting to find the focal length of a convex lens by focusing the image of a distant object on a wall is utilizing the principle that for a convex lens when the object is at an infinite distance, the image is formed at the focal point.
• If the student sees a blurry image, this indicates that the image is not precisely located on the wall. In this case, adjusting the position of the lens may be required.
• Move the lens away from the wall: If the lens is forming the image in front of the wall, then moving the lens further away from the wall can help bring the image into focus on the wall.
• Move the lens towards the wall: If the image is forming behind the wall, bringing the lens closer to the wall can place the image on the wall, again improving focus.
• So, the possibility of moving the lens either closer or further from the wall depends on the current position of the lens.

Hence, the correct answer The lens could be moved either away or toward the wall depending on its position.

The Correct answer is Swallowing → partial digestion → chewing → complete digestion.

Explanation:

• Grazing animals like cows, buffaloes, and deer are known as ruminants.
• Cows, buffaloes, and other ruminants (grass-eating animals) swallow the food continuously even when they are not eating.
• This is essentially an adaptation that these animals have developed in order to consume food as quickly as possible while avoiding predators.
• Actually, they quickly swallow the grass and store it in a part of the stomach called the rumen.
• Here, the food gets partially digested and is called cud.
• But later the cud returns to the mouth in small lumps.
• In this process, these animals again start chewing cud. This process is called rumination.
• The grass is rich in cellulose, a type of carbohydrate.
• In ruminants like cattle, deer, etc., bacteria present in the rumen help in the complete digestion of cellulose.

Thus the correct order of terms that describes the process of nutrition in ruminants is swallowing → partial digestion → chewing of cud → complete digestion.

The Correct answer is Towards both positively charged rod as well as negatively charged rod.

Concept:

• Water is a dipolar molecule, with a positive end and a negative end. When a positively charged rod comes near water, the water's negatively charged end is attracted, causing the stream to bend towards the rod. Similarly, when a negatively charged rod is near, the water's positively charged end is attracted, also bending the stream towards the rod.
• The stream of water will bend towards both the positively charged rod and the negatively charged rod.

Explanation:

• Water is a dipolar molecule, meaning it has a positive end and a negative end. This is due to the presence of hydrogens (positive) and oxygen (negative) within the structure of a water molecule.
• When you bring a positively charged rod near water, the negatively charged oxygen end in the water molecules will be attracted, causing the water stream to bend towards the rod. Conversely, when a negatively charged rod is brought near, the positively charged hydrogen end in the water molecules will be attracted, again causing the water stream to bend towards the rod.
• The bending occurs because the water molecules rearrange (or, more specifically, rotate) to align with the electric field created by the charged rod, which creates a net force pulling the water towards the rod.
• This realignment is possible because water is a polar molecule, which means it has an imbalance of charge (+ve on one side and -ve on another side) even though it's overall a neutral molecule.

Regardless of whether the rod is positively or negatively charged, the stream of water bends towards the rod due to these electrostatic interactions.

The Correct answer is (A) - Infiltration ; (B) - Aquifer.

Explanation:

• Process of seeping of water in the ground: This is infiltration, where water on the ground surface enters the soil. Infiltration depends on the permeability of the ground surface and is a part of the natural water cycle.
• Groundwater stored between layers of hard rock below the water table: This is a description of an aquifer. Aquifers are underground layers of water-bearing rock, either permeable rock or unconsolidated materials (sand, silt, etc.), from which groundwater can be extracted using a water well.
• The groundwater in these aquifers is recharged from the surface; it may percolate down from rain or snow melt or from rivers and lakes.

Additional Information Aquifer:

• An aquifer refers to an underground layer of permeable rock, sand, or gravel that holds and transmits groundwater.
• While aquifers can be a source of water supply, they are not surface water sources.

Rock fissures water:

• Rock fissures water refers to water that is found in cracks or fissures within rocks. While it is a type of groundwater, it is not a surface water source.

Recharged groundwater:

• Recharged groundwater refers to groundwater that has been replenished by natural processes, such as infiltration of rainfall or surface water. It is also a type of groundwater and not a surface water source.

The Correct answer is  It involves transfer of pollen from anther to stigma.

Explanation:

• Pollination is the process where pollen grains (which contain male gametes or sperm cells) are transferred from the anther (the male part of a flower) to the stigma (the female part of a flower), of the same species.
• It involves the transfer of pollen from anther to ovule: Incorrect. Pollen grains don't directly reach the ovule. They land on the stigma from where they grow a tube down to the ovule.
• It involves the transfer of pollen from the anther to the ovary: Incorrect. Again, pollen grains are not directly transferred to the ovary. They first land on the stigma. The ovary is then fertilized by the sperm cell traveling down the pollen tube.
• It involves the transfer of pollen from one stigma to another: Incorrect. Pollination is the transfer of pollen from the anther to the stigma, not the other way around. This option describes the opposite of what happens in pollination.

Additional Information

• The sexual reproductive part of angiosperms is called a flower.
• It develops after the completion of the vegetative phase.
• The flower contains a male part and a female part.
• The male part is known as the stamen and the female part is known as the pistil.
• Stamen is having 2 parts:
• Anthers -
• It is a two-lobed structure that contains male spores called microsporangia for the production of pollen grains.
• The anther contains pollen grains that have male gametes.
• These pollen grains need to be moved to a part of the pistil called the stigma.
• Stamen supports the anther.
• Filaments -
• It is a long stalk-like structure that connects the base of the flower with an anther that holds the anther in position.
• The female part or pistil consists of Ovary, stigma, and style.
• They are usually located in the center of the flower.
• It is having 3 parts;
• Stigma-
• It receives the pollen grains.
• It has a sticky surface and pollen grains get stuck to it during pollination.
• Style-
• It is a long tube-like structure, that connects the stigma with the ovary.
• Ovary-
• It is the basal swollen part of the pistil that contains ovules and eggs.

The Correct answer is Step A is a chemical change and Step B is a physical change.

Concept:

Physical change:

• Properties such as shape, size, color, and state of a substance are called its physical properties.
• A change in which a substance changes its physical properties is called a physical change.
• A physical change is generally reversible. In such a change no new substance is formed.
• Freezing of water, Mixing of iron filings and sand is a physical change as no new substance is formed and the change is reversible.

Chemical Change:

• A change in which one or more new substances are formed is called a chemical change.
• A chemical change is also called a chemical reaction.
• A chemical change is generally irreversible.
• Growth of a plant, Rusting of iron, Cooking of food, Burning of a candle, etc. are all chemical changes as these are irreversible.
• The conversion of milk into curd is also an irreversible change. This means that the curd cannot be converted back into milk.
• The lactic acid that coagulates the casein also denatures the casein, which means that the protein is permanently changed

Explanation:

• Step A involves the addition of sulphuric acid to copper sulfate powder and a small amount of hot water. This is a chemical change because a new substance, an acidic copper sulfate solution, is formed.
• Step B is the cooling of the solution from step A, resulting in blue-colored crystals (copper sulfate crystals). This is a physical change because it involves a change in the state of the substance (from a solution to a solid) without forming any new substances

The Correct answer is (i) - (b), (ii) - (c), (iii) - (a), (iv) - (d)

Explanation:

• Oxalic acid is found in many fruits and vegetables but is especially high in foods like spinach, beet leaves, and rhubarb. Among these, it's also found in tomatoes (b)12
• Formic acid is a naturally occurring organic acid that can be found in many insect stings, including those of bees.
• Maleic acid is not naturally found in high concentrations in specific foods like the other acids on this list. Maleic acid is found in apples, though in small amounts.
• Acetic acid is the component that gives vinegar its characteristic sour taste and pungent smell.

T he Correct answer is S1 is false but S2 is true.

Concept: 

• The pitch or shrillness of a sound is related to its frequency, which is the number of vibrations or cycles per second.
• The amplitude of sound vibrations, on the other hand, refers to the magnitude or strength of the vibrations.
• Higher amplitudes generally correspond to louder sounds.

Explanation:

• In actuality, tightening the strings on sitar increases, not decreases, the pitch of the sound it produces. The increased tension in the string increases the frequency of the vibrations, which results in a higher-pitched sound. therefore S1 is incorrect.
• The pitch of the sound produced by a vibrating string does indeed depend on the tension in the string. Greater tension in the string results in faster vibrations and a higher pitch, while lesser tension results in slower vibrations and a lower pitch. therefore S2 is correct.

 So, the correct answer is S1 is false but S2 is true 

Additional Information

• Pitch and loudness are two distinct characteristics of sound.
• Pitch is determined by frequency, while loudness is determined by the amplitude of the sound wave.
• Higher amplitudes correspond to louder sounds, whereas higher frequencies result in higher-pitched sounds.

The Correct answer is Only (D).

Concept:

• The process by which organisms exchange gases between their body cells and the environment is known as respiration.
• Respiration is of two types:
• Aerobic respiration:
• Aerobic respiration is a type of cellular respiration that occurs in the presence of oxygen and produces energy.
• Anaerobic respiration:
• Anaerobic respiration is another type of cellular respiration that occurs in the absence of oxygen and produces energy.

Explanation:

• Sometimes when we do heavy exercise such as fast running, cycling, walking, and weightlifting we require a lot of energy to meet the energy requirement of our body, which causes an impermanent lack of oxygen in the muscle cells.
• In the absence of oxygen, our bodies perform anaerobic respiration, in which glucose in muscle cells is converted into lactic acid.
• In this process, energy is produced but in a smaller amount.
• Glucose →Lactic acid + energy (in smaller amounts)

Additional Information

The Correct answer is The iron nail will behave like a temporary magnet.

Explanation:

• When the switch is closed, an electric current will flow through the coil of wire. This current will create a magnetic field around the coil. The iron nail is made of a material called ferromagnetic material, which means that it is easily magnetized. The magnetic field from the coil will magnetize the iron nail, making it behave like a temporary magnet.
• The magnetic field around the coil will be strongest at the center of the coil, which is also where the iron nail is located. This means that the iron nail will be most strongly magnetized at the center.
• When the switch is opened, the electric current will stop flowing through the coil. This will cause the magnetic field around the coil to collapse, and the iron nail will lose its magnetism.
• So, the iron nail will behave like a temporary magnet, and its magnetism will disappear when the switch is opened.

Critical thinking is the ability to think clearly and rationally about a problem or issue. It involves being able to identify the strengths and weaknesses of different arguments, to evaluate evidence, and to form your own conclusions.

Key Points

• When students are willing to review their work and identify areas for improvement, they are demonstrating critical thinking skills.
• They are showing that they are able to think about their work objectively and to identify areas where they can improve.
• This is an important skill for students to develop, as it will help them to be successful in school and in life.
• Similarly, when students are able to identify the aspects that are for and against the method adopted, they are also demonstrating critical thinking skills.
• They are showing that they are able to think about a problem from different perspectives and to weigh the pros and cons of different solutions.
• This is an essential skill for students to develop, as it will help them to make informed decisions in all areas of their lives.

Hence, we can conclude that willingness to review work done for its further improvement and identifying the aspects that are for and against the method adopted should be emphasized by teachers for the development of critical thinking among students.

A scientific theory is a well-substantiated and comprehensive explanation of some aspect of the natural world that is based on a body of evidence, observations, experimentation, and logical reasoning.

Key Points

• "A good scientific theory must be non-falsifiable" does not describe science and its processes accurately.
• Falsifiability is an important concept in science, and it is often used to distinguish between good scientific theories and bad scientific theories.
• A falsifiable theory is one that can be disproven by evidence. If a theory is not falsifiable, then it is not scientific.
• There are many examples of good scientific theories that are falsifiable.
• For example, the theory of gravity is falsifiable. If we were to find an object that was not affected by gravity, then this would falsify the theory of gravity.

Hence, we can conclude that a good scientific theory must be non-falsifiable does not describe science and its processes accurately.

Key Points

 Liquids Evaporate on heating,

• An inference is a conclusion that is drawn from evidence.
• In the case of statement (A), the evidence is that liquids evaporate on heating.
• The conclusion is that the heat causes the molecules of the liquid to move faster and faster, until they have enough energy to escape from the liquid's surface.

Pressure is inversely proportional to volume at constant temperature and number of gas moles,

• A concept is a general idea or principle.
• In the case of statement (B), the concept is the ideal gas law.
• The ideal gas law states that the pressure of a gas is inversely proportional to its volume at constant temperature and number of gas moles.

​Hence, we can conclude that statement (A) is an inference and statement (B) is a concept.

An alternative conception, also known as a "misconception" or "alternative framework," refers to an incorrect or incomplete understanding that a student or individual holds about a specific concept, idea, or principle, typically in the context of education, particularly in science or mathematics.

Key Points

• The statement "Shiny objects reflect more light than dull objects" is an alternative conception.
• It is an idea that is held by many people, but it is not always correct.
• The statement is based on the idea that shiny objects have a smooth surface that reflects light, while dull objects have a rough surface that absorbs light.
• This is why shiny objects appear to be brighter than dull objects.
• However, it is important to note that this is just an alternative conception, and it is not always correct.
• For example, a black object is very dull, but it absorbs all light and does not reflect any light.
• There are many factors that affect how much light is reflected by an object.
• These factors include the material of the object, the surface roughness of the object, and the angle of incidence of the light.
• In general, shiny objects do reflect more light than dull objects, but there are exceptions to this rule.

Hence, we can conclude that the statement "Shiny objects reflect more light than dull objects" is an alternative conception.

Key Points

 S1 : Science undergoes paradigm shifts,

• S1 states that science undergoes paradigm shifts.
• This means that there are times when the scientific community abandons an old theory and adopts a new one.
• This can happen when there is a significant amount of evidence that the old theory is incorrect.

​S2 : When several anomalous observations have accumulated, the existing theory is in a state of crisis,

• S2 states that when several anomalous observations have accumulated, the existing theory is in a state of crisis.
• This means that the theory is no longer able to explain all of the available evidence.
• This can lead to a paradigm shift, as scientists begin to look for a new theory that can explain the anomalous observations.
• In this case, S2 is the correct explanation for S1. The accumulation of anomalous observations led to a crisis in the existing theory, which eventually led to a paradigm shift.

Hence, we can conclude that both statements S1 and S2 are true and S2 is the correct explanation for S1.

Empirical evidence refers to information that is gained through direct observation, measurement, or experimentation. It is evidence that is collected from real-world observations and experiences, rather than relying solely on theory or speculation.

Key Points

• The given excerpt highlights the importance of empirical evidence in science.
• In the above situation Franklin's experiments were based on empirical evidence.
• He observed that lightning and the spark from clothes were both accompanied by a loud noise and a flash of light.
• He also observed that lightning could be attracted to a metal object, such as a key.
• Franklin concluded that lightning was caused by the same phenomenon as the spark from clothes, which is the discharge of static electricity.
• Franklin's experiments were not the only evidence that led to our understanding of lightning.
• Scientists have also observed lightning using instruments such as lightning detectors.
• These instruments measure the electric charge in the clouds and the ground, and they can also detect the flashes of light that accompany lightning strikes.
• The combination of empirical evidence from experiments and observations has led us to our current understanding of lightning.
• This is a good example of how science is based on empirical evidence.

Hence, we can conclude that the given excerpt highlights the importance of empirical evidence in science.

Scientific temper, also known as scientific attitude or scientific mindset, refers to the intellectual and open-minded approach to understanding the world that is based on scientific principles, rational thinking, and empirical evidence.

Key PointsExploring the immediate environment through inquiry, encouraging students to ask questions, and fostering the values of truth, through experimentation and open-mindedness are all helpful activities for inculcating scientific temper among students:

• Fostering the values of truth, through experimentation and open-mindedness is essential for scientific temper. Science is based on the idea that knowledge is provisional and that it can always be changed in light of new evidence. When students are taught to value truth and to be open-minded, they are more likely to be willing to question their own beliefs and to accept new evidence, even if it contradicts their previous beliefs.
• Encouraging students to ask questions is also important for inculcating scientific temper. When students are encouraged to ask questions, they are more likely to be open to new ideas and to new ways of thinking. They are also more likely to be critical of the information that they are given.
• Exploring the immediate environment through inquiry helps students to develop their curiosity and their ability to think critically. When students are encouraged to explore their surroundings, they are forced to ask questions and to come up with their own explanations for what they see. This helps them to develop their own understanding of the world, rather than simply accepting what they are told.

Hence, we can conclude that exploring the immediate environment through inquiry, encouraging students to ask questions, and fostering the values of truth, through experimentation and open-mindedness are all helpful activities for inculcating scientific temper among students:

Rust is a type of corrosion that occurs when iron reacts with oxygen in the presence of water. The oxygen and water molecules react with the iron to form iron oxide, which is the reddish-brown substance that we call rust.

Key Points

• Moist air is necessary for rusting because it provides the water molecules that are needed for the reaction to occur.
• Boiled water does not contain any dissolved oxygen, so an iron nail would not rust if it were kept in boiled water.
• To help the student design an investigation to test this hypothesis, I would suggest that they do the following:
• Obtain three iron nails.
• Label the nails A, B, and C.
• Place nail A in a container of boiled water.
• Place nail B in a container of tap water.
• Place nail C in a container of air.
• Leave the nails in their respective containers for a week.
• Observe the nails at the end of the week and record your observations.
• The student should expect to see that the nail in the container of tap water will have rusted the most, followed by the nail in the container of air.
• The nail in the container of boiled water should not have rusted at all.

Hence, we can conclude that a teacher should assist the student in designing an investigation involving placing the nails in different conditions and report findings to the class.

The inquiry approach is an educational method that places a strong emphasis on active learning, exploration, and critical thinking. It encourages students to ask questions, investigate topics, and seek answers through hands-on experiences, research, and problem-solving.

Key PointsThe correct order for carrying out the tasks in the inquiry approach to identify substances using a dissolving test would be:

• Task B: Students see an animation to help explain that substances are made of different atoms and, as a result, dissolve differently. This step provides essential background knowledge about the concept of solubility, the composition of substances, and how different atoms and molecules interact with solvents.
• Task A: Students are given unknown samples marked a, b, c, and d, consisting of sugar, salt, alum, and sand. These samples will be used in the investigation to test their solubility in different liquids.
• Task C: Students check the solubility of substances a, b, c, and d in different liquids. This is the hands-on part of the inquiry where students conduct experiments, record observations, and draw conclusions based on the solubility behavior of each substance in various solvents.

Hence, we can conclude that (B) → (A) → (C) would be the correct order for carrying out the following tasks.

Democratic science, often referred to as "science for the people" or "publicly engaged science," embodies the idea that scientific research and knowledge should be accessible, inclusive, and responsive to the needs and concerns of the broader society.

Key PointsCharacteristics of democratic science classroom:

• Students are encouraged to ask questions
• Teacher provides a safe space for students to express themselves.
• Students conduct their own experiments.
• Teacher cultivates an understanding of cultural diversity among students.
• The teacher acts as a facilitator.
• Teacher provides opportunities to students to discuss processes of decision-making and question the basis of their decision.
• The classroom is inclusive.

Hence, we can conclude that teacher plays the role of moral authority to maintain discipline does NOT characterize a democratic science classroom.