Final answer:
The σ bond between the carbon atoms in HCCH is formed by the overlap of the sp hybrid orbitals on each carbon atom.
So, correct option C) between a hybrid sp^2 orbital on C and a hybrid sp² orbital on the other C
Step-by-step explanation:
The orbitals that overlap to form the σ bond between the carbon atoms in HCCH (acetylene) are the sp hybrid orbitals. In acetylene, each carbon atom is sp hybridized and each has two unhybridized p orbitals remaining.
The sp hybrid orbitals on each carbon overlap end to end to form the σ bond between the carbon atoms. The two unhybridized p orbitals on each carbon overlap side by side to form two π bonds. Therefore, the correct answer is B) between a hybrid sp orbital on C and a hybrid sp orbital on the other C.
This results in a triple bond between the two carbon atoms, consisting of one σ bond and two π bonds.
C) between a hybrid sp² orbital on C and a hybrid sp² orbital on the other C
In the molecule ethyne (HCCH), the carbon atoms are bonded by a triple bond. The sigma (
σ) bond in the triple bond is formed by the overlap of a hybrid sp² orbital on one carbon atom with another hybrid sp² orbital on the other carbon atom. This sigma bond results from the head-on overlap of these orbitals along the internuclear axis.
So, option C correctly describes the orbitals that overlap to form the sigma (
σ) bond between the carbon atoms in HCCH.