Question

If the molar conductance values of \( \text{Ca}^{2+} \) and \( \text{Cl}^- \) at infinite dilution are respectively \( 18.88 \times 10^{-4} \, \text{m}^2 \, \text{mol}^{-1} \) and \( 77.33 \times 10^{-4} \, \text{m}^2 \, \text{mol}^{-1} \), then that of \( \text{CaCl}_2 \) is (in \( \text{m}^2 \, \text{mol}^{-1} \))

• A. \( 18.88 \times 10^{-4} \)
• B. \( 154.66 \times 10^{-4} \)
• C. \( 273.54 \times 10^{-4} \)
• D. \( 196.21 \times 10^{-4} \)

Hint:

The molar conductance of a salt is the sum of the conductances of its ions at infinite dilution.

Answer 1

The Correct Option is C

Step 1: Formula for molar conductance of salts.
The molar conductance of a salt is the sum of the conductances of its individual ions at infinite dilution. Thus, for \( \text{CaCl}_2 \), the total molar conductance is the sum of the individual conductances of \( \text{Ca}^{2+} \) and \( \text{Cl}^- \).

Step 2: Conclusion.
Thus, the molar conductance of \( \text{CaCl}_2 \) is \( 273.54 \times 10^{-4} \, \text{m}^2 \, \text{mol}^{-1} \).

Final Answer: \[ \boxed{\text{(C) } 273.54 \times 10^{-4} \, \text{m}^2 \, \text{mol}^{-1}} \]