Fill in the blanks:
$(i)$ In $1927$,Heitler and London proposed the ........ theory.
$(ii)$ The ${\rm{ClF}}_3$ molecule has a .... shape.
$(iii)$ The number of bonding pairs in ions with a square planar shape is .......... .
$(iv)$ The value of the dipole moment in ${\rm{HBr}}$ is .......... .

Identify the thermal decomposition reactions that evolve a gas containing an equal number of $\sigma$ and $\pi$ bonds.
$(a)$ $BeCO_3 \xrightarrow{\Delta } BeO + CO_2$
$(b)$ $Fe_2(SO_4)_3 \xrightarrow{\Delta } Fe_2O_3 + 3SO_3$
$(c)$ $FeSO_4 \xrightarrow{\Delta } Fe_2O_3 + SO_2 + SO_3$
$(d)$ $(NH_4)_2Cr_2O_7 \xrightarrow{\Delta } Cr_2O_3 + N_2 + 4H_2O$
$(e)$ $ZnSO_4 \xrightarrow{\Delta } ZnO + SO_3$
$(f)$ $NH_4Cl \xrightarrow{\Delta } NH_3 + HCl$

Which of the following pairs of molecules have almost identical bond dissociation energy?

Choose the correct order of $C-C$ bond length in the given compounds.

Match List-$I$ with List-$II$ :

List-$I$	List-$II$
$(A)$ $C_{2}H_{4}$	$(I)$ $3\sigma$ bonds, $2\pi$ bonds
$(B)$ $C_{2}H_{2}$	$(II)$ $3\sigma$ bonds, $1$ lone pair
$(C)$ $CH_{4}$	$(III)$ $4\sigma$ bonds
$(D)$ $NH_{3}$	$(IV)$ $5\sigma$ bonds, $1\pi$ bond

Choose the correct answer from the options given below :

The correct order of $O-O$ bond length in $O_{2}$, $H_{2}O_{2}$ and $O_{3}$ is