Correct Option: (b) Y

Step 1 (Governing Principle & Definition): [0.5 Mark]

The molar conductivity ($\Lambda_m$) of an electrolyte depends on the degree of dissociation. According to the Kohlrausch Law and the behavior of electrolytes upon dilution:

• Strong Electrolytes: These are completely dissociated in solution. Upon dilution, the increase in $\Lambda_m$ is very small (typically 1.1 to 1.5 times) because the number of ions remains constant, and the increase is only due to the reduction in inter-ionic attractions.
• Weak Electrolytes: These are poorly dissociated. Upon dilution, the degree of dissociation ($\alpha$) increases significantly according to Ostwald’s Dilution Law, leading to a sharp increase in $\Lambda_m$.

Step 2 (Step-by-Step Logical Analysis): [0.25 Mark]

Comparing the given data based on the principles of electrolytic behavior:

• For electrolyte X: $\Lambda_m$ increases 25 times. This large increase indicates a significant rise in the number of ions due to increased dissociation, characteristic of a weak electrolyte.
• For electrolyte Y: $\Lambda_m$ increases only 1.5 times. This small increase is characteristic of a strong electrolyte, where the number of ions is already at its maximum at higher concentrations.

Step 3 (Final Concluded Answer): [0.25 Mark]

Since electrolyte Y shows a minimal increase in molar conductivity upon dilution, it is already highly dissociated at higher concentrations. Therefore, Y is the stronger electrolyte.

💡 EL10 Concept Insight: Think of a strong electrolyte like a group of people who are already standing far apart; giving them more room (dilution) doesn't change much. A weak electrolyte is like a crowded room where people are stuck together; giving them more room allows them to spread out and move freely, which causes a huge change in their "conductivity."