Reversible reactions and equilibria

Ammonia is made by the Haber process.
$$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \quad \Delta H = -92 \text{ kJ/mol}$$

(a) State what is meant by a dynamic equilibrium. [2]

(b) Explain the effect of increasing the pressure on the yield of ammonia. [2]

(c) State the effect of increasing the temperature on the yield of ammonia. [1]

Dinitrogen tetroxide (colourless) and nitrogen dioxide (brown) form an equilibrium mixture in a sealed syringe.
$$\text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g) \quad \Delta H = +58 \text{ kJ/mol}$$

(a) The syringe is placed in hot water. Predict and explain the colour change of the mixture. [3]

(b) The plunger is pushed in at constant temperature, increasing the pressure. Explain what happens to the amount of NO₂ in the equilibrium mixture. [2]