Which one of the following compounds is hypervalent?

How many bonds are present between carbon and oxygen in $CO_2$? Explain.

The $X-X$ bond length is $1.00 \mathring{A}$ and $C-C$ bond length is $1.54 \mathring{A}$. If $EN$ of $X$ and $C$ are $3.0$ and $2.0$ respectively,the $C-X$ bond length is likely to be ............ $\mathring{A}$.

The electronic configuration of three elements $A$,$B$ and $C$ are given below. Stable form of $C$ may be represented by the formula
$A : 1s^2, 2s^2, 2p^6$
$B : 1s^2, 2s^2, 2p^6, 3s^2, 3p^3$
$C : 1s^2, 2s^2, 2p^6, 3s^2, 3p^5$

$AlCl_3$,in reactions,acts as

Which of the following sulphur compounds follows the octet rule?