Write the balanced chemical equations and explain the preparation, properties, and uses of hydrogen gas.

here are the answers to the questions:

a) The equation for the reaction between zinc and dilute hydrochloric acid is:

$$\boxed{\text{Zn(s)} + 2\text{HCl(aq)} \rightarrow \text{ZnCl}_2\text{(aq)} + \text{H}_2\text{(g)}}$$

b) An appropriate drying agent for hydrogen gas is concentrated sulfuric acid or anhydrous calcium chloride.

c) Copper metal cannot be used to prepare hydrogen gas from dilute acids because copper is less reactive than hydrogen in the reactivity series. Therefore, it cannot displace hydrogen from dilute acids.

d) Hydrogen burns in oxygen to form an oxide (water).

i) The equation for the reaction is:

$$\boxed{2\text{H}_2\text{(g)} + \text{O}_2\text{(g)} \rightarrow 2\text{H}_2\text{O(l)}}$$

ii) Two precautions that must be taken are:

1. Before combustion begins: Test the hydrogen gas for purity (e.g., using the 'pop' test) to ensure it is free from air, as a mixture of hydrogen and air is explosive.
2. At the end of combustion: Continue passing hydrogen gas until the apparatus has cooled down to prevent suck-back of air into the hot apparatus, which could cause an explosion.

e) Two uses of hydrogen gas are:

1. As a fuel (e.g., in rockets or fuel cells).
2. In the Haber process for the industrial production of ammonia.