Question

evaluate understanding what did i learn? bond length and energy comparing the length of carbon - carbon covalent bonds c - c c = c c ≡ c 147 pm 134 pm 120 pm 347 kj mol^{-1} 614 kj mol^{-1} 839 kj mol^{-1} which of the following types of bonds will have the longest bond length? a) c - h single bond b) c = c double bond c) c ≡ c triple bond d) n ≡ n triple bond

Explanation:

Step1: Recall bond length trends

In general, for bonds between the same type of atoms (like carbon - carbon bonds shown in the image), single bonds ($C - C$) are longer than double bonds ($C = C$), and double bonds are longer than triple bonds ($C\equiv C$). Also, when comparing bonds between different atoms, the size of the atoms matters. Hydrogen is a very small atom. The $C - H$ single bond is formed between a carbon atom and a hydrogen atom.

Step2: Analyze each option

• Option A: $C - H$ single bond. Carbon and hydrogen are relatively small atoms, but the single - bond nature (compared to double and triple bonds of carbon - carbon) and the fact that in carbon - carbon bonds (from the image $C - C$ is 147 pm, $C = C$ is 134 pm, $C\equiv C$ is 120 pm), and when we consider $C - H$, the $C - H$ bond length is around 109 pm. Wait, no, actually, let's re - think. The key is that for bonds: single bonds are longer than double bonds which are longer than triple bonds. Among the given options, we have a $C - H$ single bond (A), $C = C$ double bond (B), $C\equiv C$ triple bond (C), and $N\equiv N$ triple bond (D). But if we consider the general rule that single bonds are longer than multiple bonds (double and triple).

Answer:

A. C - H single bond