Question

The ionic mobilities of the cation and the anion of a salt $A_{2}B$ are 140 and 80 $oh{m}^{-1}c{m}^{2}e{q}^{-1}$ respectively.The molar conductivity of salt at infinite dilution (in $oh{m}^{-1}c{m}^{2}eq-1$) is:

• A. 160
• B. 220
• C. 60
• D. 360

Answer 1

The correct option is D 360

According to kohlrausch law of independent migration of ions, the molar conductivity of an electrolyte at infinite dilution is equal to the sum of the contributions of the molar conductivities of its ions.
Hence,
${\Lambda }_{A2B}^{\infty }=n^{+}{\Lambda }_{A+}^{\infty }+n^{-}{\Lambda }_{B2-}^{\infty }$
Substitute the values in the above equation.
${\Lambda }_{A2B}^{\infty }=2\times 140+80=360{ohm}^{-1}{cm}^2{eq}^{-1}.$

Hence, option D is correct.