Question

What is the main constituent of coal gas?

• A. Oxygen
• B. Water
• C. Nitrogen
• D. Methane

Hint:

Think about how coal gas is manufactured, by heating coal with no air supply.

Answer 1

The Correct Option is D

Step 1: Coal gas is made by heating coal strongly in the absence of air. This process is called destructive distillation.

Step 2: During this heating, the coal breaks down and releases a mixture of gases. This mixture contains hydrogen, methane, carbon monoxide and small amounts of other gases like ethylene and nitrogen.

Step 3: Among the given options, methane is the real combustible fuel gas present in coal gas in a large amount. It is the gas that burns and gives useful heat and light, so it is treated as the main constituent here.

Step 4: Now check the wrong options. Oxygen is not present as a free gas in coal gas because coal gas is made by heating coal away from air. Water only appears as moisture or steam, not as a fuel component. Nitrogen is present only as an inert diluent gas, it does not burn and does not add fuel value.

Step 5: So option D, methane, is correct.