Bond length of ethane $(I)$, ethene $(II)$, acetylene $(III)$ and benzene $(IV)$ follows the order

Which of the following molecules can show Lewis acidity?
$(I)$ $CO_2$ $(II)$ $Br_2$ $(III)$ $SnCl_2$ $(IV)$ $HF$ $(V)$ $NMe_3$

With what neutral molecule is $ClO^{-}$ isoelectronic? Is that molecule a Lewis base?

Match the following molecules in Column $I$ with the number of lone pairs on their central atom in Column $II$.

Column $I$ (Molecules)	Column $II$ (Number of lone pairs on central atom)
$A. \ NH_3$	$1. \ \text{Two}$
$B. \ H_2O$	$2. \ \text{Three}$
$C. \ XeF_2$	$3. \ \text{Zero}$
$D. \ CH_4$	$4. \ \text{Four}$
	$5. \ \text{One}$

Number of molecules from the following which are exceptions to the octet rule is. . . .
$CO_2, NO_2, H_2SO_4, BF_3, CH_4, SiF_4, ClO_2, PCl_5, BeF_2, C_2H_6, CHCl_3, CBr_4$

In which of the following compounds is the octet complete $(C)$ or incomplete $(IC)$ for all atoms?
$Al_2Cl_6$ $-$ $Al_2(CH_3)_6$ $-$ $AlF_3$ $-$ Dimer of $BeCl_2$ $-$ Dimer of $BeH_2$
(Note: $C$ for complete octet and $IC$ for incomplete octet.)