Temperature of maximum density of $\mathrm{H}_2 \mathrm{O}$ is $y \mathrm{~K}$ and $\mathrm{D}_2 \mathrm{O}$ is $x \mathrm{~K} .(x-y)($ in K$)$ is nearly

Oxidation state of hydrogen in compound $X$ is -1 and in compound $Y$ is $+1 . X$ and $Y$ are respectively