In the molecule $C_2{H}_2$ (ethyne), how many carbon atoms are $\mathrm{sp}$ hybridized?

• A. $2$
• B. $0$
• C. $4$
• D. $1$

Answer: (A)

Verified step by step guidance

1. Identify the molecular formula and structure of ethyne, which is C\_2H\_2. Ethyne is also known as acetylene and consists of two carbon atoms triple bonded to each other, with each carbon atom bonded to one hydrogen atom.
2. Recall the concept of hybridization: hybridization describes the mixing of atomic orbitals to form new hybrid orbitals suitable for bonding. The type of hybridization depends on the number of regions of electron density around the atom.
3. Determine the hybridization of each carbon atom in ethyne. Each carbon forms two sigma bonds (one with hydrogen and one with the other carbon) and has two pi bonds (part of the triple bond). This corresponds to two regions of electron density, which is characteristic of sp hybridization.
4. Conclude that both carbon atoms in ethyne are sp hybridized because each has two regions of electron density (one sigma bond to hydrogen and one sigma bond in the triple bond), with the remaining two p orbitals forming pi bonds.
5. Therefore, the number of sp hybridized carbon atoms in ethyne is equal to the total number of carbon atoms, which is 2.