JEE Main levelSingle correct optionDifficulty 2 of 3sb044
Assertion (A): A concentrated solution of sodium in liquid ammonia is diamagnetic.
Reason (R): At high concentration all the ammoniated electrons remain unpaired and their spins align in the same direction.
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: C
Concentrated metal-ammonia solutions are indeed diamagnetic, so A is true. The reason is that the ammoniated electrons associate and pair up with opposite spins, not that they remain unpaired and aligned. So R is false.