Explanation
- A
1 and 2 only
(a) 1 and 2 only. Statement 1 (warming can destabilise hydrates and release methane) and statement 2 (Indian continental shelves host hydrate deposits, as in KG and Andaman surveys) are true, but statement 3 is also true, so 1-and-2 is not the key.
- B
2 and 3 only
(b) 2 and 3 only. Drops the valid warming–release statement, so this is not the key.
- C
1 and 3 only
(c) 1 and 3 only. Drops the valid Indian-shelf statement, so this is not the key.
- D
1, 2 and 3
(d) 1, 2 and 3. Methane hydrates in continental-margin sediments can release methane if warmed; India has surveyed large shelf deposits; methanotrophic bacteria oxidise methane in the water column and thus reduce the methane that reaches the air. All three listed claims hold, so this is the official key.
Summary. Official key is (d) 1, 2 and 3. Gas hydrates are ice-like methane cages in cold, pressured shelf and slope muds. Warming is a release risk; India has hydrate provinces on its shelves; microbes eat much of the leaking methane. Honour the stored letter (d).
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
-
2016 · Q97 · General Studies · 2 marks
With reference to the Agreement at the UNFCCC Meeting in Paris in 2015, which of the following statements is/are correct? 1. The Agreement was signed by all the member countries of the UN and it will go into effect in 2017. 2. The Agreement aims to limit the greenhouse gas emissions so that the rise in average global temperature by the end of this century does not exceed 2°C or even 1.5°C above pre-industrial levels. 3. Developed countries acknowledged their historical responsibility in global warming and committed to donate $1000 billion a year from 2020 to help developing countries to cope with climate change. Select the correct answer using the code given below -
2022 · Q44 · General Studies · 2 marks
In the context of WHO Air Quality Guidelines, consider the following statements: 1. The 24-hour mean of PM 2.5 should not exceed 15 µg/m3 and annual mean of PM2.5 should not exceed 5 µg/m3. 2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather. 3. PM10 can penetrate the lung barrier and enter the bloodstream. 4. Excessive ozone in the air can trigger asthma. Which of the statements given above are correct?