CAIE IGCSE Chemistry 6.3 Reversible Reactions and Equilibrium Topic Practice

When the colourless gas $\mathrm{N}_{2} \mathrm{O}_{4}$ is heated, it forms the brown gas $\mathrm{NO}_{2}$.
When the reaction mixture is cooled, the brown colour fades and turns back to colourless.
Which type of reaction is described by these observations?

Some information about three gases, P, Q and R, is listed.
- Gas P forms when magnesium reacts with dilute hydrochloric acid.
- Gas Q makes up 78% of the air.
- Gas R forms when gas P reacts with gas Q.

What is gas R ?

Which statements about the Haber process are correct?
1 One of the raw materials is extracted from liquid air by fractional distillation.
2 One of the raw materials is produced by the reaction of steam and methane.
3 The catalyst for the Haber process is vanadium(V) oxide.