Statement I :  C – Cl bond is stronger than Cl – Cl bond.

Statement II : C – H bond is stronger than C – Cl bond.

Bond enthalpy of $\mathrm{C}–\mathrm{H}>\mathrm{C}–\mathrm{C}>\mathrm{C}–\mathrm{Cl}>\mathrm{Cl}–\mathrm{Cl} ;$ ;

Cl-Cl bond is very weak because of the repulsions between lone pairs on adjacent chlorine atoms.

Size of H-atom <  size of C-atom(both these atoms do not possess a lone pair.); 

Bond enthalpy of H-H > C-H > C-C

In general

 $\text{Bond enthalpy ∝}\frac{1}{\mathrm{size} \mathrm{of} \mathrm{atoms} \mathrm{involved} \mathrm{in} \mathrm{bonding}}$