Question

Assertion (A): First ionisation enthalpy of Cr is lower than that of Zn.
Reason (R): Zinc is a non-transition element.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Stable configs explain I.E., not classification.

Answer 1

The Correct Option is B

Cr has lower I.E. due to stable half-filled d$^5$ configuration, which is easier to ionise.
Zn has stable filled d$^{10}$ → higher I.E.
While Zn is not a transition element (due to no variable oxidation states), this fact does not explain Cr’s lower I.E.