State what are chlorofluorocarbons and give their use. Give a reason why they are ozone depleting. State a suitable alternative to chlorofluorocarbons which are non-ozone depleting.

Choose the letter corresponding to the correct answer from — A : NO₂, B : NO, C : N₂, D : N₂O

The gas obtained when –

1. Dry ammonia and dry oxygen gas are ignited together.
2. Ammonia is passed over heated litharge.
3. A greenish yellow gas reacts with excess ammonia.
4. (a) Dry NH₃ and O₂ are passed over heated Pt.
   (b) The gaseous product obtained is further oxidized.
5. Ammonium nitrite undergoes thermal decomposition.

Give balanced equations for the following conversions — A, B, C, D and E.

1. $\text{NH}$4\text{OH} \xrightarrow{\text{A}} (\text{NH}4)2\text{SO}4 \xrightarrow{\text{B}} \text{NH}_3
2. $\text{NH}$4\text{Cl} \xleftarrow{\text{C}} (\text{NH}3) \xrightarrow{\text{D}} \text{NH}_4\text{Cl}
3. $\text{NH}$3 \xrightarrow{\text{E}} \text{N}2

Give reasons for the following:

An aqueous solution of ammonia acts as a weak base.