Van't Hoff factor for $\mathrm{Na}_2 \mathrm{SO}_4 \cdot 10 \mathrm{H}_2 \mathrm{O}$ solution, assuming complete ionization is

Assertion (A): Zr and Hf are of almost similar atomic radii.

Reason (R): This is due to lanthanoid contraction.

Assertion (A): The units of rate constant of a zero order reaction and rate of reaction are the same.

Reason (R): In zero order reaction, the rate of reaction is independent of the concentration of reactants.

Assertion (A): Inversion of configuration is observed in $\mathrm{S}_{\mathrm{N}} 2$ reaction.

Reason (R): The reaction proceeds with the formation of carbocation.