Question

Given below are two statements:
Statement I: Diamagnetic \(li_2\) molecules are known to exist in the vapour phase.
Statement II: According to MO theory, double bond in \(C_2\) consists of both \( \pi \) bonds. The correct option is:

• A. Both statements I and II are correct.
• B. Both statements I and II are not correct.
• C. Statement I is correct, but statement II is not correct.
• D. Statement II is correct, but statement I is not correct.

Hint:

Always confirm the electronic configurations and molecular orbital theory descriptions when analyzing bond characteristics in molecules.

Answer 1

The Correct Option is A

To solve the problem, let's evaluate the two given statements:

Statement I: "Diamagnetic Li₂ molecules are known to exist in the vapor phase."
This statement is correct. Lithium (Li) has two electrons, and when two lithium atoms form a molecule (Li₂), the two electrons pair up in the bonding molecular orbital, resulting in no unpaired electrons. As a result, Li₂ is diamagnetic and can exist in the vapor phase under appropriate conditions.

Statement II: "According to M.O theory, the double bond in C₂ consists of both π bonds."
This statement is incorrect. In the molecule \( C_2 \), the bonding involves both sigma and pi bonds. According to Molecular Orbital (M.O.) theory, the double bond in \( C_2 \) consists of one sigma bond and one pi bond, not two pi bonds. Therefore, Statement II is incorrect.

Conclusion: Since Statement I is correct, but Statement II is not.

Final Answer:
The correct option is (C) Statement I is correct, but Statement II is not correct.