Question

Following figure shows dependence of molar conductance of two electrolytes on concentration. Λ^o _m is the limiting molar conductivity. The number of incorrect statement(s) from the following is ________ 

(A) \(\Lambda \text{o m}\) for electrolyte A is obtained by extrapolation. 
(B) For electrolyte B, \(\Lambda \text{m}\) vs \(\sqrt c\) graph is a straight line with intercept equal to o \(\Lambda \text{m}\)
(C) At infinite dilution, the value of degree of dissociation approaches zero for electrolyte B. 
(D) Λo m for any electrolyte A or B can be calculated using \(\lambda0\) for individual ions.

Hint:

For molar conductance:
Strong electrolytes show a linear dependence of \(\Lambda_m\) on \(\sqrt{C}\), with gradual decreases at higher concentrations.
Weak electrolytes exhibit non-linear dependence due to incomplete ionization, with \(\Lambda_m\) leveling off as concentration increases.

Answer 1

Correct Answer: 2

1. Analysis of the Graph:
The graph shows the molar conductance \(\Lambda_m\) vs. \(\sqrt{C}\) for two electrolytes, A and B. 
A exhibits a linear decrease in \(\Lambda_m\) with \(\sqrt{C}\), characteristic of a strong electrolyte.
B exhibits a sharp decrease, leveling off at higher concentrations, characteristic of a weak electrolyte.
2. Key Points to Identify the Incorrect Statements:
Statement 1: "Electrolyte A is a strong electrolyte because \(\Lambda_m\) extrapolates linearly to \(\Lambda_m^\circ\)." 
\[Incorrect. \quad \text{Strong electrolytes show linear dependence on } \sqrt{C}.\]
Statement 2: "Electrolyte B is a weak electrolyte, as \(\Lambda_m\) does not extrapolate linearly to \(\Lambda_m^\circ\)."
\[Correct. \quad \text{Weak electrolytes exhibit non-linear behavior due to incomplete dissociation.}\]
Statement 3: "For strong electrolytes, \(\Lambda_m\) decreases significantly with increasing \(\sqrt{C}\)."
\[Incorrect. \quad \text{For strong electrolytes, the decrease in \(\Lambda_m\) with increasing \(\sqrt{C}\) is gradual, not significant.}\]
Statement 4: "Weak electrolytes exhibit a sharp decrease in \(\Lambda_m\) at low concentrations due to incomplete dissociation."
\[Correct. \quad \text{This behavior is due to the concentration dependence of ionization.}\]
3. Number of Incorrect Statements:
Only Statement 3 is incorrect. Statements A and C are correct.