Question

Given below are two statements :
Statement I : The limiting molar conductivity of $KCl$ (strong electrolyte) is higher compared to that of $C{H}_{3}COOH$ (weak electrolyte).
Statement II : Molar conductivity decreases with decrease in concentration of electrolyte.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Statement I is true but Statement II is false.
• B. Statement I is false but Statement II is true.
• C. Both Statement I and Statement II are true.
• D. Both Statement I and Statement II are false.

Answer 1

Answer: (D)

Ion	$H^{+}$	$K^{+}$	$C{l}^{-}$	$C{H}_{3}CO{O}^{-}$
${\Lambda }_{mSc{m}^2/mole}^{\infty }$	349.8	73.5	76.3	40.9

So ${\Lambda }_{mC{H}_{3}COOH}^{\infty }={\Lambda }_{m\left(H^{+}\right)}^{\infty }+{\Lambda }_{mC{H}_{3}CO{O}^{-}}^{\infty }$
$=349.8+40.9$
$=390.7Sc{m}^2/mole$
${\Lambda }_{mKCl}^{\infty }={\Lambda }_{m\left(K^{+}\right)}^{\infty }+{\Lambda }_{m\left(C{l}^{-}\right)}^{\infty }$
$=73.5+76.3$
$=149.3Sc{m}^2/mole$
So statement-I is wrong or False.
As the concentration decreases, the dilution increases which increases the degree of dissociation, thus increasing the no. of ions, which increases the molar conductance.
So statement-II is false.