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Statement-1: The H2 molecule is more stable than the HeH molecule. Statement-2: In HeH the extra electron occupies an antibonding orbital, lowering the bond order and hence the stability. Choose the correct option.

1. Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1.
2. Statement-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1
3. Statement-1 is true, statement-2 is false.
4. Statement-1 is false, statement-2 is true.

Correct answer: Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1.

Solution

H2 has bond order 1 (2 bonding e-), while HeH has 2 bonding and 1 antibonding e-, giving bond order 0.5; the antibonding electron correctly explains the lower stability.

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