Arrange the following components of biogas in decreasing order of their abundance.

1.Ammonia (NH3)

2.Hydrogen sulphide (H2S)

3.Methane (CH4)

4.Carbon dioxide (CO2)

A2, 4, 1, 3

B3, 4, 1, 2

C4, 3, 2, 1

D3, 4, 2, 1 ✓ Correct

Correct answer: (D) 3, 4, 2, 1

Explanation

Methane is the most abundant component of biogas, usually making up more than half of it.

Carbon dioxide comes next, forming roughly a third of the mixture.

Hydrogen sulphide is present only in small traces well below the two main gases.

Ammonia occurs in the smallest amount of the four listed components.

The decreasing order is thus methane, carbon dioxide, hydrogen sulphide, then ammonia.

Removing hydrogen sulphide is important because it is corrosive and foul smelling.

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