JEE Main levelSingle correct optionDifficulty 2 of 3sb045
Assertion (A): Lithium has the most negative standard electrode potential of all alkali metals (−3.04V) even though it has the highest first ionisation enthalpy in the group.
Reason (R): The LiX+ ion has the highest hydration enthalpy in the group.
ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true
Answer: A
E∘ reflects the overall change M(s)MX+(aq)+eX−, which includes sublimation, ionisation and hydration. The very high hydration enthalpy of the tiny LiX+ ion more than offsets its high ionisation enthalpy. So A and R are true and R explains A.