Mix of Methane and Other Gases Found in Coal Mines
Puzzle 11 of Hinduism Hard Pack
Question is: Mix of Methane and Other Gases Found in Coal Mines
and the answer is: FIREDAMP
Word Meaning:
FIREDAMP — (mining) A flammable gas (mostly methane) found in coal mines; forms an explosive mixture with air.
Definitions from Wiktionary.