Assertion (A) : In weak electrolytes, the change in ${\mathrm{\Lambda }}_{\mathrm{m}}$ with dilution is mainly due to increase in degree of dissociation
Reason (R) : At a given concentration of weak electrolyte the degree of dissociation $\mathrm{\alpha }=\frac{{{\mathrm{\Lambda }}^0}_{\mathrm{m}}}{{\mathrm{\Lambda }}_{\mathrm{m}}}$