Oxidation of thiosulphate $S_2O_3^{2-}$ ion by iodine gives

Acidified potassium dichromate on reacting with a sulphite is reduced to

In the following reaction,$I_2 + 5Cl_2 + 6H_2O \longrightarrow X + Y$,the products $X$ and $Y$ respectively are:

Given the redox reaction:
$X Na_2HAsO_3 + Y NaBrO_3 + Z HCl \longrightarrow NaBr + H_3AsO_4 + NaCl$
The values of $X$,$Y$,and $Z$ in the balanced equation are respectively:

Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

The set of coefficients of $P_4$,$OH^{\Theta}$ and $H_2PO_2^{\Theta}$ in the balanced reaction $P_4 + OH^{\Theta} \to PH_3 + H_2PO_2^{\Theta}$ is