Arrange the following as per the instructions given in the bracket.

$\mathrm{M}\mathrm{g}, \mathrm{C}\mathrm{l}, \mathrm{N}\mathrm{a}, \mathrm{S}, \mathrm{S}\mathrm{i}$ (Decreasing order of atomic size).

Arrange the following as per the instructions given in the bracket.

$\mathrm{N}\mathrm{a}, \mathrm{K}, \mathrm{C}\mathrm{l}, \mathrm{S}, \mathrm{S}\mathrm{i}$ (Increasing order of ionisation energy).

Element $\mathrm{X}$ is a metal with a valency $2,\mathrm{Y}$ is a non-metal with a valency $3$.

(i) Write an equation to show how $\mathrm{Y}$ forms an ion?

(ii) If $\mathrm{Y}$ is a diatomic gas, write an equation for the direct combination of $\mathrm{X}$ and $\mathrm{Y}$ to form a compound.