NEETChemistryChemical Bonding and Molecular Structure
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The carbon-carbon double bond in the C ₂ molecule consists of one bond and one bond. Reason (R): In the molecular orbital configuration of C ₂ , the 2s and ^ * 2s electrons cancel each other's bonding effect, and the highest occupied orbitals are degenerate 2p_x and 2p_y containing four electrons.
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
D. (A) is not correct but (R) is correct
Step-by-step solution
According to Molecular Orbital Theory, the electronic configuration of C ₂ (12 electrons) is: 1s^2 , ^ * 1s^2 , 2s^2 , ^ * 2s^2 , 2p_x^2 = 2p_y^2 The bonding contribution of the 2s^2 electrons is cancelled by the antibonding ^ * 2s^2 electrons. The highest occupied molecular orbitals are the degenerate 2p_x and 2p_y orbitals, which contain a total of 4 electrons. Therefore, the bond order is 4 - 0 2 = 2 , and the double bond in C ₂ consists entirely of two bonds without any bond. Thus, Assertion (A) is incorrect, w