JEE Chemistry 2024 Question with Solution

Given: Statements about ethyne are to be checked.

Find: The incorrect statement.

Ethyne is $\mathrm{C_2H_2}$ and contains a carbon-carbon triple bond. In ethyne, both carbon atoms are $sp$ hybridized, so the molecule is linear.

Now analyze each statement:

1. The C-C bond in ethyne is shorter than that in ethene — this is true because a triple bond is shorter than a double bond.
2. Both carbons are $sp$ hybridized — this is true.
3. Ethyne is linear — this is true.
4. The C-C bond in ethyne is weaker than that in ethene — this is false because a carbon-carbon triple bond is stronger than a carbon-carbon double bond.

Therefore, the incorrect statement is option D.

Given: Ethyne has a carbon-carbon triple bond.

Find: Which option is incorrect.

A carbon-carbon triple bond has greater overlap than a double bond. Hence it is both shorter and stronger than the carbon-carbon double bond in ethene.

Also, each carbon in ethyne is $sp$ hybridized, which gives a linear geometry with bond angle $180^\circ$.

So, the only incorrect statement is that the C-C bond in ethyne is weaker than that in ethene. The correct option is D.