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Chemistry · 2025 · 2 marks
CBSE 2025 · Region 5 · Set 1 · Q18
Based on the data given above, give plausible reason for the variation of conductivity and molar conductivity with concentration.
| Concentration of KCl solution in $\displaystyle \mathrm{mol} / L$ | Conductivity at $\displaystyle 298 \cdot 15 K$ in $\displaystyle S c m^{-1}$ | Molar Conductivity at $\displaystyle 298 \cdot 15 K$ in $\displaystyle S \mathrm{~cm}^{2} \mathrm{~mol}^{-1}$ |
| $\displaystyle 1.000$ | $\displaystyle 0 \cdot 1113$ | $\displaystyle 111 \cdot 3$ |
| $\displaystyle 0.100$ | $\displaystyle 0.0129$ | $\displaystyle 129 \cdot 0$ |
| $\displaystyle 0.010$ | $\displaystyle 0.00141$ | $\displaystyle 141 \cdot 0$ |
Marking-scheme solution
Conductivity decreases with decrease in concentration
Due to decrease in number of current carrying ions per unit volume.
Molar conductivity increases with decrease in concentration
Due to decrease in inter-ionic attraction or increase in dissociation or increase in number of
ions.
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