Ozone layer depletion is mainly caused by: MCQ with Answer and Explanation

Ozone layer depletion is mainly caused by:
A. Carbon monoxide
B. Chlorofluorocarbons (CFCs)
C. Ammonia
D. Sulphur dioxide
Answer: Option B
Solution (By JKSSB Mock Tests)
CFCs release chlorine atoms under UV radiation in the stratosphere, which catalytically destroy ozone molecules. CO causes smog and is poisonous, SO₂ causes acid rain, ammonia is not a major ozone depleter. The Montreal Protocol phased out CFCs to protect the ozone layer.

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Practice More chemistry Questions

Question #1
Which of the following gases contributes to the greenhouse effect?
A. Hydrogen
B. Oxygen
C. Nitrogen
D. Carbon dioxide

Correct Answer: Option D


Explanation:
CO₂ is a major greenhouse gas that absorbs infrared radiation and re-emits it, warming the atmosphere. Other GHGs: CH₄, N₂O, water vapor, CFCs. N₂ and O₂ are diatomic homonuclear molecules that do not absorb IR and are not GHGs. Hydrogen is not a GHG. The increase in CO₂ due to human activities is driving climate change.

This question belongs to: Science chemistry
Question #2
Which of the following gases deviates most from ideal behavior at room temperature?
A. Nitrogen
B. Hydrogen
C. Helium
D. Ammonia

Correct Answer: Option D


Explanation:
Real gases deviate from ideal behavior due to intermolecular forces and molecular volume. Ammonia (NH3) has strong intermolecular hydrogen bonding and a relatively large molecular size compared to small, non-polar gases like He, H2, and N2. Therefore, ammonia exhibits the greatest deviation from ideal gas behavior.

This question belongs to: Science chemistry
Question #3
The reaction of an alcohol with a carboxylic acid in the presence of an acid catalyst to form an ester is called:
A. Fermentation
B. Saponification
C. Esterification
D. Hydrogenation

Correct Answer: Option C


Explanation:
Esterification is the chemical reaction where a carboxylic acid reacts with an alcohol in the presence of a strong acid catalyst (like conc. H₂SO₄) to produce an ester and water. Saponification is the reverse process, involving the alkaline hydrolysis of esters to form soap and glycerol.

This question belongs to: Science chemistry