Ques. 1JEE Main 2024, 1 February (Evening Shift)
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below :
- (A) is true but (R) is false
- Both (A) and (R) are true and (R) is the correct explanation of (A)
- Both (A) and (R) are true but (R) is not the correct explanation of (A)
- (A) is false but (R) is true
Answer
(2) Both (A) and (R) are true and (R) is the correct explanation of (A)
Solution
Cr2+ (d4) Cr3+ (d3, half-filled t2g3) ⇒ Cr2+ is reducing
Mn3+ (d4) Mn2+ (d5, half-filled) ⇒ Mn3+ is oxidising ⇒ (A) is true
∵ both changes lead to an extra-stable half-filled configuration ⇒ (R) is true and explains (A)
Answer: (2)