how to identify gases

Question 1

how to prove gases by physical properties

Answer 1

colour and odor, density and state (some are odourless and colourless while others have a distinct colour or smell)

Question 2

how to prove the identity of hydrogen

Answer 2

using a lit splint to test for hydrogen

Question 3

how to identify oxygen

Answer 3

relighting a glowing splint for oxygen

Question 4

how to identify carbon dioxide

Answer 4

using limewater to detect carbon dioxide