2.39 describe tests for the gases

Hydrogen
Squeaky pop test - put a lit splint into a test tube of gas. If it makes a 'squeaky pop' sound, hydrogen is in the tube.

Oxygen
Oxygen will relight  glowing splint.

Carbon Dioxide
If bubbled through limewater the limewater will go cloudy if carbon dioxide is present.

Ammonia
Damp red litmus paper will turn blue if ammonia is present.

Chlorine
Turns damp blue litmus paper red, then white (as it bleaches).