The variation of \(\Lambda _m\) with \(\sqrt{c}\) for a strong electrolyte is shown in the graph. Identify the correct representation for the same
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → graph D
For a strong electrolyte, the molar conductivity increases only slowly on dilution and follows the Debye–Hückel–Onsager equation:
\( \displaystyle \Lambda_m = \Lambda^\circ_m - A\sqrt{c} \)
This has the form y = c + mx with a negative slope (−A). So a plot of Λm against √c is a straight line falling from the intercept Λ°m, which is graph D.
A weak electrolyte, such as acetic acid, gives instead a steep curve near zero concentration, because its degree of dissociation rises sharply on dilution.
NCERT (2026-27 edition):
Strong Electrolytes
