Search Previous Year Questions

The correct option is 1.

Key Points

• J.J Thomson has proposed that an atom is electrically Neutral due to the presence of protons and electrons inside the nucleus.
• Electrons have a negative charge, whereas there is a positive charge for protons.
• An atomic number is defined as the number of protons present in the nucleus. It is denoted by the letter Z.
• Isotopes are those elements that have the same atomic no. but different mass no.
• Some radioactive isotopes like Cobalt - 60 are used in the medical treatment of fatal diseases like cancer.
• Uranium - 235 is used for nuclear fission and the production of electricity.
• Radioactive isotopes are used for the detection of cracks (leakage) in underground pipes. Example: Sodium-24.

Confusion Points

• Atom is electrically neutral due to protons and neutrons embedded inside the nucleus and electrons spinning around the nucleus.
• Electrons are not present inside the nucleus.
• Therefore statement 1 is an incorrect statement.

CONCEPT:

Acrylic:

• Acrylic is a synthetic fiber.
• Acrylic is commonly known as synthetic wool because it mimics wool.
• Acrylic is used to make sweaters, blankets, and a variety of other garments.
• They are also used to fill soft toys and pillows and produce garments.

Rayon:

• It is Also called “Artificial silk”.
• Obtained by chemical treatment of wood pulp. Wood Pulp is a natural source.
• Rayon is an artificial fiber that is very cheap compared to real silk.
• It Can be woven like silk fibers and can be dyed in a wide range of colors.

​Teflon:

• It is a brand name for a synthetic chemical called polytetrafluoroethylene (PTFE).
• It was first made in 1938 by Roy J. Plunkett to create a non-reactive, nonstick surface.
• It’s known for its use in cookware, although it can also be used to coat other materials like wires or fabrics to make them waterproof.

It is a suspected carcinogen, hormone disruptor, and reproductive toxin.

​EXPLANATION:

From the above, it is clear that acrylic is known as synthetic wool, and rayon is known as artificial silk. 

The correct option is 3.

The correct option is 

EXPLANATION:

• Diamond and graphite are the two allotropes of carbon.
• Diamond is having high melting and boiling point is true. Also, it is one of the hardest known substances.
• carbon atoms in diamonds have a strong bond in three dimensions.
• Graphite is a good conductor of electricity but it is soft as non-metal, So, graphite is not hard.
• Graphite is soft as compared to a diamond and The soft slippery nature and high resistance to heat make graphite useful.
• In graphite, each atom of carbon is surrounded by three other carbon atoms by single bonds, thereby forming a layer of hexagonal structures while diamond has a tetrahedral arrangement.
• Both Graphite and diamond being the allotropes of the same element, carbon, have similar chemical properties. So they undergo the same chemical reactions.

The correct option is  Butane.

EXPLANATION:

• The gas, which we use in our home for the preparation of food is called liquid petroleum gas.
• The main constituents of LPG are the liquid form of butane and isobutane.
• Liquefied petroleum gas (LPG) is a combination of propane and butane.
• It is odorless that's why Ethyl Mercaptan is added to it so there may be a smell if LPG leaks from its storage container.

Additional Information

• Water Gas :
• Water-gas is a mixture of CO and H2.
• However, by-products such as char, tar, soot, ash, and condensates are also produced.
• Natural gas (also called fossil gas; sometimes just gas), is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium.
• Compressed natural gas is a fuel that can be used in place of petrol (gasoline), diesel fuel, and liquefied petroleum gas (LPG).
• CNG combustion produces fewer undesirable gases than the aforementioned fuels.
• In comparison to other fuels, natural gas poses less of a threat in the event of a spill, because it is lighter than air and disperses quickly when released.

The correct option is osmosis.

EXPLANATION:

• Soil moisture is not only needed by plants for growth but it is also the solvent through which the cations or nutrients essential to plants are brought to the plant roots.
• The plant roots then take in the nutrients through their root-cell membranes, following the process called osmosis.
• Water passes from the soil into the roots by a physical process called osmosis.

The correct option is bacteria.

Concept:

Biodegradable wastes:

• The wastes that can be degraded or decomposed in nature by the action of different microbes and other living things using processes like composting, aerobic digestion, anaerobic digestion, etc are called Biodegradable wastes.
• Examples include wood, fruits, vegetables, dead animal and plants, etc.
• These wastes majorly include organic matter which can be broken down into simpler organic molecules like carbon dioxide, methane, and water.
• However, some Inorganic matters are also included which can be degraded by microbial action like gypsum.

​Non-biodegradable wastes:

• The wastes that cannot be degraded or decomposed in nature by the action of different microbes and other living things using processes like composting, aerobic digestion, anaerobic digestion, etc are called Non-Biodegradable wastes.
• These wastes act as a source of environmental pollution.
• Examples include plastic, glass, metallic wastes, etc.

​Explanation:

• Biodegradable waste is converted into a useful substance through the bioremediation process.
• Bioremediation is a branch of biotechnology that employs the use of living organisms, like microbes and bacteria, in the removal of contaminants, pollutants, and toxins from soil, water, and other environments. Bioremediation is used to clean up oil spills or contaminated groundwater.

The correct option is they liberate carbon dioxide.

EXPLANATION:

• Trees take in Oxygen and omit Carbon-dioxide at night. This will create an insufficiency of Oxygen for a man who is sleeping under the tree.
• In the nighttime, it is advised not to sleep under trees because they liberate carbon dioxide.

The correct answer is Nitrogen.

Concept:

• Carnivorous plants obtain the essential nutrients from the heterotrophs.
• These plants trap insects and obtain the nutrients which they do not get from the soil as they grow in nitrogen-deficient soils.
• They are not called heterotrophs or consumers, because they only derive nutrients from insects.
• These plants get energy from the process of photosynthesis.
• Hence they are both producers and carnivores.

Key Points

• Insectivorous plants are plants that feed on insects.
• Insectivorous plants grow in nitrogen-deficient soils.
• They obtain nitrogen from different insects, e.g. Drosera, Nepenthes, Dionne, Utricularia, etc.

The correct option is 5 (More than one of the above)

EXPLANATION

Stem: It is a link between the roots, the leaves, and the flowers. The stem of a tree is called a trunk. The point on the stem from where a leaf or another branch grows is called the node and the portion of the stem between the two nodes is called the internode.

Functions of stem:

(a) It carries water and minerals from the roots to the different parts of the plant..(b) It carries the food made by leaves to the other parts of the plant.

(c) It supports branches, flowers, and fruits.

(d) Stem modifications can be of various types based on the following functions:

• Support - Tendrils that are spirally coiled for supporting climbers.
• Storage - Potato tubers, a rhizome of ginger.
• Protection - Thorns of Bougainvillea.
• Photosynthesis - Phylloclade of cactus that contain chlorophyll for photosynthesis.
• Vegetative propagation - Runner, stolon, and offset that give rise to new plants.

The correct option is the Rh factor.

EXPLANATION:

• A blood transfusion is a routine medical procedure in which donated blood is provided to you through a narrow tube placed within a vein in your arm. This potentially life-saving procedure can help replace blood lost due to surgery or injury.
• During a blood transfusion, a healthcare professional will place a small needle into the vein, usually in the arm or hand. The blood then moves from a bag, through a rubber tube, and into the person's vein through the needle.
• They will carefully monitor vital signs throughout the procedure.
• Some doctors believe that hospital patients who fall below 10 g/dL should get a blood transfusion. But recent research found that: Many patients with levels between 7 and 10 g/dL may not need a blood transfusion. One unit of blood is usually as good as two, and it may even be safer.
• If you have type AB blood, you can receive any type of blood and you’re called a universal recipient. If you have Rh-negative blood, you can only receive Rh-negative blood.
• So, In a transfusion, blood must be compatible not only in blood type but also with the Rh factor