Mark the element which shows only one oxidation state.

Arrange the acids $(I)$ $H_2SO_3$,$(II)$ $H_3PO_3$,and $(III)$ $HClO_3$ in the decreasing order of acidity.

Predict the formula 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

The maximum valency of an element with atomic number $7$ is

Assertion : $HClO_4$ is a stronger acid than $HClO_3$.
Reason : Oxidation state of $Cl$ in $HClO_4$ is $+VII$ and in $HClO_3$ is $+V$.

Identify the element which can have the highest oxidation number among the given options.