An element $(A)$ occurs in the short period having electronic configuration $ns^2 np^1$. The formula of its oxide will be

Using Stock notation,represent the following compounds: $HAuCl_{4}$,$Tl_{2}O$,$FeO$,$Fe_{2}O_{3}$,$CuI$,$CuO$,$MnO$,and $MnO_{2}$.

Consider the following information about elements $P$ and $Q$:

Element	Period and Group
$Q$	Period $2$,Group $15$
$P$	Period $3$,Group $2$

Then the formula of the compound formed by $P$ and $Q$ elements is:

Which of the following elements exhibits variable oxidation states?

Select the $CORRECT$ order of stability.

Predict the formulas of the stable binary compounds that would be formed by the combination of the following pairs of elements.
$(a)$ Lithium and oxygen
$(b)$ Magnesium and nitrogen
$(c)$ Aluminium and iodine
$(d)$ Silicon and oxygen
$(e)$ Phosphorus and fluorine
$(f)$ Element $71$ and fluorine