Q: The gas which destroys ozone layer is:

A: Oxygen

B: Argon

C: Chloroflurocarbon

D: Hydrogen



Correct Option: C  [ Chloroflurocarbon ]

Remark:

Explanation: Chlorofluorocarbons (CFCs) are the gases responsible for the depletion of the ozone layer. When released into the atmosphere, CFCs break down under ultraviolet (UV) radiation, releasing chlorine atoms that destroy ozone molecules (O₃), leading to thinning of the ozone layer and increased UV radiation reaching the Earth.


Q: Which of the following statements is not true about Bt cotton ?

A: Bt cotton has increased profit margin of farmers

B: Use of insecticides has reduced significantly

C: Seeds of Bt cotton are cheaper than non-GM seeds

D: Since the use of Bt cotton India's cotton export has doubled.



Correct Option: C  [ Seeds of Bt cotton are cheaper than non-GM seeds ]

Remark:

Explanation: Mucor is not a biofertilizer; it is a saprophytic fungus that grows on decaying organic matter. Biofertilizers are living microorganisms that enhance soil fertility by fixing atmospheric nitrogen or solubilizing nutrients. Examples include Rhizobium, Azotobacter, and Anabaena.


Q: The first nuclear test conducted by India under the code name of "Smiling Buddha" was in the year:

A: 1973

B: 1974

C: 1975

D: 1976



Correct Option: B  [ 1974 ]

Remark:


Q: What is common in AIDS, hepatitis and typhoid fever ?

A: All are bacterial disease

B: All are water borne diseases

C: All are viral disease

D: All are spread by human beings



Correct Option: D  [ All are spread by human beings ]

Remark:

Explanation: AIDS, Hepatitis, and Typhoid fever are all diseases that can be spread by human beings. While AIDS and Hepatitis are viral diseases and Typhoid is a bacterial disease, all three are transmitted through contact with infected individuals or their body fluids, making human-to-human transmission common.


Q: Alcohol contains :

A: nitrogen, hydrogen, oxygen

B: carbon, hydrogen, oxygen

C: oxygen, carbon, nitrogen

D: hydrogen, chlorine, oxygen



Correct Option: B  [ carbon, hydrogen, oxygen ]

Remark:

Explanation: Alcohols are organic compounds composed of carbon (C), hydrogen (H), and oxygen (O). They are characterized by the presence of one or more hydroxyl (-OH) functional groups attached to a carbon atom. The general formula of alcohols is CnH2n+1OH. A common example is ethanol (C₂H₅OH), which is used in beverages, fuels, and sanitizers. The -OH group makes alcohols polar, soluble in water (especially lower alcohols), and reactive in many organic reactions.


Q: Number of spinal nerves in human are:

A: 11 pairs

B: 27 pairs

C: 32 pairs

D: 31 pairs



Correct Option: D  [ 31 pairs ]

Remark:

Explanation: In humans, the spinal cord gives rise to 31 pairs of spinal nerves. Each spinal nerve is a mixed nerve containing both sensory and motor fibers. They are divided into groups based on the region of the vertebral column from which they originate:

  • 8 pairs — Cervical nerves
  • 12 pairs — Thoracic nerves
  • 5 pairs — Lumbar nerves
  • 5 pairs — Sacral nerves
  • 1 pair — Coccygeal nerve

These spinal nerves connect the central nervous system (CNS) to different parts of the body, transmitting sensory information to the brain and motor commands to muscles.


Q: The mountaineers carry oxygen with them because:

A: at an altitude of more than 5 km there is no air

B: the amount of air available to a person onmountain is lesser than that available on the ground

C: the temperature of air is lesser than that onthe ground.

D: The pressure of air is higher than that on theground.



Correct Option: B  [ the amount of air available to a person onmountain is lesser than that available on theground ]

Remark:

Mountaineers carry oxygen cylinders because the amount of air (and oxygen) available at high altitudes is much less than that at ground level. As altitude increases, air pressure and oxygen concentration decrease, making breathing difficult and leading to altitude sickness. Supplemental oxygen helps them breathe properly and maintain body function.

  • No air above 5 km: Incorrect — air exists but is thinner.
  • Lower temperature: True but not the reason for carrying oxygen.
  • Higher air pressure: Incorrect — pressure decreases with height.


Q: Entomology is the science that studies:

A: The origin and history of technical and scientific terms.

B: Insects

C: The formation of Rocks

D: Behavoiur of human beings



Correct Option: B  [ Insects ]

Remark:

Explanation: Entomology is a branch of Zoology that focuses on the study of insects, including their structure, classification, behavior, ecology, and evolution. Insects make up more than 75% of all known animal species on Earth and play crucial roles in pollination, decomposition, and food chains. Scientists who study insects are known as entomologists.


Q: What is the temperature when density of water is the highest

A: 5 degree Celsius

B: 6 degree Celsius

C: 4 degree Celsius

D: 3 degree Celsius



Correct Option: C  [ 4 Degree Celsius ]

Remark:

Explanation: Water shows an unusual property known as anomalous expansion. Its density is maximum at 4°C. When cooled from higher temperatures, water contracts till 4°C, becoming denser. Below 4°C, it expands instead of contracting, so its density decreases. This property allows ice to float and prevents water bodies from freezing solid, protecting aquatic life during winters.


Q: One (1) molecule of CFC deplete __________ molecule of Ozone in the Ozonosphere.

A: 1,00,000

B: 10,000

C: 10,00,000

D: No one of the above



Correct Option: A  [ 1,00,000 ]

Remark:

One molecule of a Chlorofluorocarbon (CFC) can destroy up to 1,00,000 molecules of ozone (O₃) in the ozone layer. When CFCs reach the stratosphere, they are broken down by ultraviolet (UV) radiation, releasing chlorine atoms. Each chlorine atom acts as a catalyst in the breakdown of ozone molecules, significantly depleting the protective ozone layer that shields Earth from harmful UV rays.

Other options (for context)

  • 10,000: Underestimates the destructive potential of a single CFC molecule.
  • 10,00,000: Overestimates the number of ozone molecules destroyed.
  • No one of the above: Incorrect — the correct answer is 1,00,000 molecules of ozone.
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