Clear Chemical With Pungent Smell Used in Cleaning
Puzzle 12 of Running a Marathon Pack
Question is: Clear Chemical With Pungent Smell Used in Cleaning
and the answer is: AMMONIA
Word Meaning:
AMMONIA — (inorganic chemistry) A gaseous, toxic compound of hydrogen and nitrogen, NH₃, with a pungent smell and taste.
Definitions from Wiktionary.