$\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ are hydroxy-compounds of the elements $\mathrm{P}, \mathrm{Q}$ and $\mathrm{R}$ respectively. $\mathrm{P}, \mathrm{Q}$ and $\mathrm{R}$ are in the same period of the periodic table. $\mathrm{A}$ gives an aqueous solution of $\mathrm{pH}<7$. $\mathrm{B}$ reacts with both strong acids and strong alkalies. $\mathrm{C}$ gives an aqueous solution which is strongly alkaline. Which of the following statement(s) is /are true?

$\text{I}$ . All three elements are metals.
$\text{II}$ . The atomic radius decreases in the order $\mathrm{P}>\mathrm{Q}>\mathrm{R}$.
$\text{III}$ . The electronegativities decrease from $\mathrm{P}>\mathrm{Q}>\mathrm{R}$.
$\text{IV}$. $\mathrm{P}, \mathrm{Q}$ and $\mathrm{R}$ could be $\mathrm{P}, \mathrm{Al}$ and $\mathrm{Na}$ respectively.