Science
Assertion (A) : The amount of ozone in the atmosphere began to drop sharply in the 1980s.
Reason (R) : The oxygen atoms combine with molecular oxygen to form ozone.
options
- (A) and (R) are true and (R) is the reason for (A).
- (A) and (R) are true and (R) is not the reason for (A).
- (A) is true, but (R) is false.
- (A) is false, but (R) is true.
Answer
(A) and (R) are true and (R) is not the reason for (A).
Reason —
Assertion (A) is true because scientific studies in the 1980s showed a significant depletion of the ozone layer, particularly over Antarctica due to the release of chlorofluorocarbons (CFCs) and other pollutants, which break down ozone molecules in the stratosphere, leading to the formation of the ozone hole.
Reason (R) is true because it describes how ozone is naturally formed in the atmosphere (O + O2 → O3). However, it does not explain why the ozone amount dropped in the 1980s. The drop was due to ozone destruction by CFCs, not its natural formation process.
Hence, (A) and (R) are true and (R) is not the reason for (A).
Related Questions
Assertion (A) : A human child bears all the basic features of human beings.
Reason (R) : It looks exactly like its parents, showing very little variations.
options
- (A) and (R) are true and (R) is the reason for (A).
- (A) and (R) are true and (R) is not the reason for (A).
- (A) is true, but (R) is false.
- (A) is false, but (R) is true.
Assertion (A) : No two magnetic field lines are found to cross each other.
Reason (R) : The compass needle cannot point towards two directions at the point of intersection of two magnetic field lines.
options
- (A) and (R) are true and (R) is the reason for (A).
- (A) and (R) are true and (R) is not the reason for (A).
- (A) is true, but (R) is false.
- (A) is false, but (R) is true.
A student performs the following experiment in his school laboratory.
List two observations to justify that in this experiment a chemical change has taken place.
Draw labelled diagrams to show different stages of budding in Hydra.