The specific conductance of a decinormal KCl solution is 0.0121 ohm^-…

The correct answer is Option (1) → \( 0.6776\, cm^{-1} \)

The resistance of a solution in a conductivity cell depends on the distance l between the electrodes and their area A. The ratio \( l/A \) is the cell constant, \( G^{*} \), and it links the measured resistance to the conductivity (specific conductance) \( \kappa \):

    \( \displaystyle \kappa = \frac{1}{R} \times \frac{l}{A} = \frac{G^{*}}{R} \)

    \( \displaystyle G^{*} = \kappa \times R \)

Substituting \( \kappa = 0.0121\,\mathrm{ohm^{-1}\,cm^{-1}} \) and \( R = 56\,\mathrm{ohm} \):

    \( \displaystyle G^{*} = 0.0121\,\mathrm{ohm^{-1}\,cm^{-1}} \times 56\,\mathrm{ohm} = 0.6776\,\mathrm{cm^{-1}} \)

So the cell constant is 0.6776 cm⁻¹. This is how a cell constant is found in practice: a KCl solution of known conductivity is placed in the cell and its resistance is measured.