Ozone Layer and Its Depletion MCQs

Q1. Which everyday change helps protect the ozone layer?

• A.using more aerosol cans with CFCs
• B.burning more fossil fuels
• C.using CFC-free refrigerators and sprays
• D.releasing old AC gas to air

Answer: C. using CFC-free refrigerators and sprays

Q2. Consider the following statements about the ozone layer: (I) Ozone absorbs harmful UV radiation. (II) CFCs deplete the ozone layer. (III) Ozone is found in the Earth's core. Which of the above statement(s) is/are correct?

• A.None of these
• B.Only I and II
• C.Only I
• D.Only III

Answer: B. Only I and II

NCERT fact (biology, chapter 'Our Environment'): Extraction sequence: concentration of ore -> roasting / calcination -> reduction (C, Al thermite, or electrolysis) -> refining; pick the step / agent suited to the metal's position in the reactivity series; substituting the named metal here => the listed match emerges; hence the answer = Only I and II. Why option B fits - Correct. Distractor analysis: option A) 'None of these' misses the point - Re-check each statement individually; option C) 'Only I' is wrong because Re-check each statement individually. Final answer - B) Only I and II.

Q3. A student looking at a model of the atmosphere asks at which layer the protective ozone shield is concentrated; what is the correct answer?

• A.In the mesosphere above the stratosphere
• B.At the Earth's surface only
• C.In the troposphere near the ground
• D.In the stratosphere

Answer: D. In the stratosphere

The protective ozone layer is concentrated in the stratosphere, the second atmospheric layer, roughly 15-35 km above the ground.