Main constituents of coal gas are-

1. ${\mathrm{H}}_2\mathrm{O},{\mathrm{C}}_2{\mathrm{H}}_6,{\mathrm{O}}_2$

2. ${\mathrm{CH}}_4,{\mathrm{CO}}_2,{\mathrm{O}}_2$

3. ${\mathrm{CH}}_4,{\mathrm{H}}_2,\mathrm{CO}$

4. ${\mathrm{C}}_2{\mathrm{H}}_6,{\mathrm{N}}_2,{\mathrm{O}}_2$

The correct option is C

${\mathrm{CH}}_4,{\mathrm{H}}_2,\mathrm{CO}$

Explanation:

• Coal gas is one of the main products obtained by the destructive distillation of coal.
• It is a mixture of gases that contains hydrogen (${\mathrm{H}}_2$), methane (${\mathrm{CH}}_4$), and carbon monoxide ($\mathrm{CO}$).
• It is known as an excellent fuel.
• The main usage of coal gas was in lighting houses, factories, and streets.

Thus, the main constituent of coal gases are:

${\mathrm{CH}}_4,{\mathrm{H}}_2,\mathrm{CO}$

Final answer:

Hence, option (C) is correct.