NH3
Else clues• Cleaning agent
• Cleaning compound
• Cleaning-solution ingredient
• Colorless gas
• Common chemical fertilizer
• Common cleanser
• Compound used in smelling salts
• Fertilizer ingredient
• Floor polish ingredient
• Household cleaning chemical
• Household cleaning item
• It's lighter than air
• Nitrogen-hydrogen compound
• Primordial soup ingredient
• Pungent gas
• Pungent liquid
• Rejected scratch 'n' sniff sticker #2
• Smelling salts ingredient
• Strong-smelling cleaning ingredient
• Strong-smelling cleaning solution
• Suffocating solution
• The smell of clean
• Unbreathable part of an atmosphere
• A pungent gas compounded of nitrogen and hydrogen (NH3)