✓ Board-verified
Science · 2025 · 1 mark
CBSE 2025 · Region 1 · Set 1 · Q20
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…
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.
Official answer
(B)
Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
All Our Environment questions2025 question paperNCERT solutions: Our EnvironmentPractice Our Environment →
More from Our Environment
- Assertion (A): Ozone (O_3) gas at higher levels of atmosphere is a product of UV radiation acting on Oxygen (O_2). Reason (R): The amount of ozone in…2026
- Why are the organisms of first trophic level important in any food chain? Justify the following statement: 'The flow of energy in an ecosystem is…2025
- Assertion: Producers are capable of using light energy from the sun to make food available in an ecosystem. Reason (R): All food chains in an…2024
- Other than the abiotic components, which of the given biotic components are not required to make an aquarium with small herbivorous fishes a…2025
- Use of pesticides to protect our crops affect organisms at various trophic levels especially human beings. Name the phenomenon involved and explain…2024
- Explain why food chains generally consist of three or four steps.2026
- Plants → Deer → Lion In the given food chain, what will be the impact of removing all the organisms of second trophic level on the first and third…2024
- What are human-made ecosystems? Give an example. Can a human-made ecosystem become a self-sustaining ecosystem? Give reason to justify your answer.2022
CBSE Class 10 Science past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.