Chapter 6

In a flask, colourless \(\mathrm{N}_{2} \mathrm{O}_{4}\) is in equilibrium with brown coloured \(\mathrm{NO}_{2}\). At equilibrium, when the flask is heated at \(100^{\circ} \mathrm{C}\) the brown colour deepens and on cooling it becomes less coloured. The change in enthalpy, \(\Delta H\), for the system is (a) negative (b) positive (c) zero (d) undefined

For the chemical reaction: \(3 \mathrm{X}(\mathrm{g})\) \(+\mathrm{Y}(\mathrm{g}) \rightleftharpoons \mathrm{X}_{3} \mathrm{Y}(\mathrm{g})\), the amount of \(\mathrm{X}_{3} \mathrm{Y}\) at equilibrium is affected by (a) temperature and pressure (b) temperature only (c) pressure only (d) temperature, pressure and catalyst

In equilibrium: \(\mathrm{SCN}(\mathrm{aq})+\mathrm{Fe}^{+3}(\mathrm{aq}) \rightleftharpoons\left[\mathrm{Fe}(\mathrm{SCN})^{2+}\right](\mathrm{aq})\) \(\begin{array}{lll}\text { colourless } & \text { yellow } & \text { deep red }\end{array}\) If thiocyanate ions are added in equilibrium mixture (a) The solution becomes colourless. (b) The yellow colour of solution deepens. (c) The red colour of the solution deepens. (d) Concentration of \([\mathrm{Fe}(\mathrm{SCN})]^{2+}\) ion will decrease.

An aqueous solution of volume \(500 \mathrm{ml}\), when the reaction: \(2 \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s}) \rightleftharpoons\) \(\mathrm{Cu}^{2+}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{s})\), reached equilibrium, the concentration of \(\mathrm{Cu}^{2+}\) ions was \(x \mathrm{M}\). To this solution, \(500 \mathrm{~m}\) of water is added. At the new equilibrium, the concentration of \(\mathrm{Cu}^{2+}\) ions would be (a) \(2 x \mathrm{M}\) (b) \(x \underline{M}\) (c) between \(x\) and \(0.5 x \mathrm{M}\) (d) less than \(0.5 x\) M

In the equilibrium mixture: \(\mathrm{H}_{2}(\mathrm{~g})+\mathrm{I}_{2}(\mathrm{~g})\) \(\rightleftharpoons 2 \mathrm{HI}(\mathrm{g})\), the mole ratio of gases are \(\sqrt{2}: \sqrt{2}: 10\), respectively. What would be the effect on the mole ratio on adding 5 mole of He gas at constant pressure? (a) No change (b) The new molar ratio becomes \(1: 1: 5\) (c) The new molar ratio becomes \(2: 2: 5\) (d) The new molar ratio becomes \(2: 2: 5 \sqrt{2}\)