- Oxygen: relights a glowing splint
- Hydrogen: Pops when a lighted splint is put into a test tube containing hydrogen
- Carbon Dioxide: Turns limewater cloudy (calcium hydroxide + carbon dioxide --> calcium carbonate + water)
- Ammonia: Turns damp red litmus paper blue, has a pungent smell, when fumes mixed with those of hydrochloric acid create white smoke
- Chlorine: Has a characteristic smell; bleaches damp red litmus paper (after turning it blue)
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