Two solutions 'A' and 'B' are taken and diluted. On dilution, it was seen that the limiting molar conductivity of 'B' increases to a smaller extent while that of 'A' increases to a much larger extent comparatively, which of the two is a strong electrolyte?

B

The correct answer is option 1 - B
Electrolyte B is a strong electrolyte. - Molar conductivity increases on dilution for both strong and weak electrolytes, but the extent of increase is different.

• Strong electrolytes are almost completely ionised in solution.
  When diluted, the number of ions does not increase much. The increase in molar conductivity occurs mainly because inter-ionic attractions decrease, allowing ions to move more freely. Hence, the increase is small.

• Weak electrolytes are partially ionised.
  On dilution, degree of ionisation increases significantly, producing many more ions. Therefore, the molar conductivity increases to a much larger extent.

In the question:

• B shows a smaller increase in limiting molar conductivity → indicates strong electrolyte.

• A shows a much larger increase → indicates weak electrolyte.

Therefore, B is the strong electrolyte.