(a) Give reasons for the following: (i) Sulphur in vapour state shows paramagnetic behaviour: (ii) N-N bond is weaker than P-P bond: (iii) Ozone is thermodynamically less stable then oxygen. (b) Write the name of the gas released when $\mathrm{Cu}$ is added to (i) Dilute $\mathrm{HNO}_3$ (ii) Conc. $\mathrm{HNO}_3$ OR (a) (i) Write the disproportionation reaction of $\mathrm{H}_3\mathrm{PO}_3$ (ii) Draw the structure of $\mathrm{XeF}_4$.(b) Account for the following:(i) Although fluorine has less negative electron gain enthalpy yet $\mathrm{F}_2$ is a strong oxidizing agent.(ii) Acidic character decreases from $\mathrm{N}_2\mathrm{O}_3$ to $\mathrm{Bi}_2\mathrm{O}_3$ in group 15.(c) Write a chemical reaction to test sulphur dioxide gas. Write the chemical equation involved..