how does coal gas form?
Kindly refer to the following link,
https://www.meritnation.com/ask-answer/question/sorry-how-is-coal-gas-in-made-i-did-not-understand/coal-and-petroleum/5394480
https://www.meritnation.com/ask-answer/question/sorry-how-is-coal-gas-in-made-i-did-not-understand/coal-and-petroleum/5394480