JEE Main levelSingle correct optionDifficulty 2 of 3ec216
The limiting molar ionic conductivity of NaX+ is 50.1Scm2mol−1. Taking F=96500Cmol−1, the ionic mobility of NaX+ at infinite dilution is
A5.19×10−4cm2V−1s−1
B5.19×10−8cm2V−1s−1
C4.83×106cm2V−1s−1
D1.93×103cm2V−1s−1
Answer: A
For an ion of charge number z, λ∘=zuF; for NaX+, z=1 so u=λ∘/F. u=96500Cmol−150.1Scm2mol−1=5.19×10−4cm2V−1s−1 (since Scm2C−1=cm2V−1s−1). Multiplying by F instead gives 4.83×106.