Nitrogen and Hydrogen Compound With Pungent Smell
Puzzle 2 of Smelly Things Easy Pack
Question is: Nitrogen and Hydrogen Compound With Pungent Smell
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.