(a) Give a chemical test to identify the following gases :

1. Ammonia
2. Sulphur dioxide
3. Hydrogen chloride
4. Chlorine
5. Carbon dioxide
6. Oxygen
7. Hydrogen

(b) Select a basic gas mentioned in Q.1(a). How is the basic nature verified?

(c) Select acidic gases from the gases mentioned in Q.1(a). How is the acidic nature verified?

(d) State the gas responsible for the bleaching action?

(e) Which gas turns blue cobalt chloride paper light pink?

(a) Chemical test to identify the gases are :

1. Ammonia — When a glass rod dipped in conc. HCl is brought near the gas, dense white fumes of ammonium chloride are formed.
2. Sulphur dioxide — Sulphur dioxide gas turns acidified potassium permanganate from pink to clear colourless and acidified potassium dichromate from orange to clear green.
3. Hydrogen chloride — Forms a curdy white ppt. on passage through AgNO₃ solution. The precipitate dissolves in excess of NH₄OH.
4. Chlorine — Pass the gas through silver nitrate solution, a white ppt. of silver chloride is formed.
5. Carbon dioxide — When the gas is passed through lime water, it turns milky and white ppt. of calcium carbonate appears.
6. Oxygen — Oxygen gas rekindles a glowing wooden splinter.
7. Hydrogen — Hydrogen gas burns with a 'pop' sound in air.

(b) Ammonia is a basic gas. It turns red litmus blue.

(c) Sulphur dioxide, Hydrogen chloride, Chlorine, Carbon dioxide. It turns blue litmus red.

(d) Chlorine

(e) Water vapour