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 not correct but (R) is correct
- Both (A) and (R) are correct and (R) is the correct explanation of (A)
- Both (A) and (R) are correct but (R) is not the correct explanation of (A)
- (A) is correct but (R) is not correct
Answer
(4) (A) is correct but (R) is not correct
Solution
As per NCERT, the metal–carbon bond in metal carbonyls possesses both σ and π character. The M–C σ bond is formed by the donation of a lone pair of electrons on the carbonyl carbon into a vacant orbital of the metal. The M–C π bond is formed by the donation of a pair of electrons from a filled d orbital of the metal into the vacant antibonding π* orbital of carbon monoxide (synergic bonding).
Ligand → metal bond is σ and metal → ligand bond is π.
Assertion is correct; Reason states it the other way round, so Reason is not correct.
Answer: (4)