Excess ${\mathrm{Cl}}_2$ reacts with ${\mathrm{NH}}_3$ to give ‘X’. Excess ${\mathrm{NH}}_3$ reacts with ${\mathrm{Cl}}_2$ to give ‘Y’. ‘X’ and ‘Y’ are compounds of nitrogen. Oxidation states of nitrogen in ‘X’ and ‘Y’ respectively are