Name some active metals that react with steam to give hydrogen gas. Give balanced chemical equation also.

When a piece of iron is put into cupric sulphate solution, iron displaces copper and forms ferrous sulphate. This reaction is

Consider the following statements(s) regarding the preparation of hydrogen gas?

I. Reaction of potassium with cold water.

II. Reaction of calcium with boiling water.

III. Reaction of aluminium with steam

IV. Reaction of iron with boiling water or steam

The incorrect statement is 

Choose the correct word or letter from the bracket to complete the sentence.

Separation of hydrogen from carbon dioxide is achieved by passing the mixture through _____. (ammoniacal cuprous chloride, potassium hydroxide solution)

Complete the following equations:

$\mathrm{A}$: ${\mathrm{Al}}_2{\mathrm{O}}_3$

$\mathrm{B}$: ${\mathrm{Fe}}_3{\mathrm{O}}_4$

$\mathrm{C}$: ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$

Enter your correct answer as $\mathrm{A}, \mathrm{B},$ or $\mathrm{C}$.