A
1 and 3
B
3 and 4
C
2 and 3
D
1 and 2
Correct answer: (a) 1 and 3
Explanation
- A
1 and 3
1 and 3. Biogas is mostly methane (about 50–75%) plus carbon dioxide. Butane and CO are not the two majors.
- B
3 and 4
3 and 4. CO2 is present; CO is not a major constituent.
- C
2 and 3
2 and 3. Butane is LPG, not biogas.
- D
1 and 2
1 and 2. Methane yes; butane no.
Summary. Official key is (a) 1 and 3. Major biogas pair: methane and carbon dioxide. Also note: CH4 share — Typically 50–75% of biogas; CO2 share — Typically 25–50%; LPG — Propane + butane; not this mix; Gobar gas — Cattle-dung anaerobic digester.
Same topic · past papers
UPPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
-
2024 · Q108 · UPPGS
Given below are two statements, one is labelled as Assertion (A) : and the other as Reason (R). Assertion (A): CO₂, SO₂, and NO₂ gases get dissolved in rain water and produce acid rain. Reason (R): Atmospheric air is polluted due to high concentration of gases like carbon dioxide, sulphur dioxide and oxides of nitrogen. Select the correct answer from the codes given below: -
2018 · Q63 · UPPGS
Methane is emitted from which of the following?