Give a word equation for the following reaction:

Two gases which combine to give a solid.

Give a word equation for the following reaction:

A compound which on heating shows - colour change from brown to yellow.

Give a word equation for the following reaction:

A salt that reacts with ammonium hydroxide to give a reddish-brown precipitate.

Give a word equation for the following reaction:

An exothermic reaction where both the reactants are gases, one of which is oxygen.

Name the following:

The silvery residue obtained on heating mercury $\left[\mathrm{II}\right]$ oxide.

Name the following:

Two non-metals react explosively when brought into close contact.

Name the following:

Two gases react under pressure in presence of a catalyst at elevated temperatures to give a gaseous product.

Name the following:

A catalyst increases the rate of a chemical reaction. [This catalyst is the compound of Manganese]