Given below are two statements labelled as Assertion (A) and Reason (R)

These are the options for the question :Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion : Magnetic moment values of actinides are lesser than the theoretically predicted values. Reason : Actinide elements are strongly paramagnetic. Select the most appropriate answer from the options given below: a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A. c. A is true but R is false. d. A is false but R is true.

The correct answer is -b Both A and R are true but R is not the correct explanation of A. The magnetic moment is less as the 5f electrons of actinides are less effectively shielded which results in quenching of orbital contributions , they are strongly paramagnetic due to presence of unpaired electrons