Question

The incorrect statement regarding ethyne is

• A. The C–C bonds in ethyne is shorter than that in ethene
• B. Both carbons are sp hybridised
• C. Ethyne is linear
• D. The carbon-carbon bonds in ethyne is weaker than that in ethene

Answer 1

The Correct Option is D

To solve this question about the properties of ethyne, we need to analyze each statement given in the options:

1. The C–C bonds in ethyne is shorter than that in ethene: This is a true statement. In ethyne (acetylene, C₂H₂), the carbon-carbon bond is a triple bond, which is shorter than the double bond in ethene (C₂H₄).
2. Both carbons are sp hybridised: This is also true. In ethyne, each carbon atom is sp hybridized, forming a linear molecule with an angle of 180 degrees between bonds.
3. Ethyne is linear: This statement is true. Due to sp hybridization, ethyne has a linear geometry.
4. The carbon-carbon bonds in ethyne is weaker than that in ethene: This is an incorrect statement. The carbon-carbon triple bond in ethyne is stronger than the carbon-carbon double bond in ethene due to the presence of more overlapping orbitals in a triple bond.

Based on the analysis, the incorrect statement is: The carbon-carbon bonds in ethyne is weaker than that in ethene.

Answer 2

To determine the incorrect statement regarding ethyne, let's first understand its structure and properties.

• Ethyne (C₂H₂) Structure: It is an alkyne, characterized by a carbon-carbon triple bond (C≡C). The structural formula is H-C≡C-H.
• Hybridization: In ethyne, both carbon atoms are \(sp\) hybridized. This means that each carbon atom uses one \(s\) orbital and one \(p\) orbital, forming two \(sp\) hybrid orbitals.
• Geometry: The \(sp\) hybridization results in a linear geometry with a bond angle of 180°, making ethyne linear.
• Bond Length and Strength: The carbon-carbon triple bond is shorter and stronger than either a double bond (as in ethene) or a single bond, due to the presence of three shared pairs of electrons.

Now let's evaluate each provided statement:

The C–C bonds in ethyne is shorter than that in ethene

This statement is correct. The triple bond in ethyne is shorter than the double bond in ethene because triple bonds have greater electron sharing, pulling the atoms closer together.

Both carbons are sp hybridised

This is also correct. As mentioned, ethyne carbons are \(sp\) hybridized.

Ethyne is linear

This statement is correct. Due to \(sp\) hybridization, ethyne has a linear molecular shape.

The carbon-carbon bonds in ethyne is weaker than that in ethene

This statement is incorrect. The carbon-carbon bond in ethyne (triple bond) is stronger than that in ethene (double bond) due to the triple bond having more shared electron pairs, making it stronger.

Conclusion: The incorrect statement is: "The carbon-carbon bonds in ethyne is weaker than that in ethene." The correct fact is that the carbon-carbon bond in ethyne is actually stronger.