Question

The triple bond in ethyne is made up of:
(A) Three sigma bonds
(B) Three pi bonds
(C) One sigma and two pi bonds
(D) Two sigma and one pi bonds

Answer 1

Hint: A single bond represents the presence of one sigma bond. A double bond represents the presence of one sigma and one pi bond. A triple bond represents the presence of one sigma bond and two pi bonds. Ethyne has a triple bond character.

Complete Step by Step Solution:
Hydrocarbons are organic compounds that consist of only carbon and hydrogen atoms. These are classified into three types based on the bonding character involved. These are alkanes, alkenes, and alkynes. Alkanes are saturated hydrocarbons that have a single bond character. Saturation represents the single bond character. Alkenes are unsaturated hydrocarbons that have a double bond character. Alkynes are also unsaturated hydrocarbons that have a triple bond character. Unsaturation represents the multiple bond character.

The given molecule ethyne belongs to alkynes. The general molecular formula of alkynes is \[{C_n}{H_{2n - 2}}\] where \[n\] represents the number of carbon atoms. The molecular formula of ethyne is \[{C_2}{H_2}\]. The common name of ethyne is acetylene. As ethyne belongs to alkynes, it has a triple bond character. Out of the three bonds, one is the sigma bond and the other two are pi bonds.
Option c is the correct answer.

Note: In any molecule or a chemical compound that consists of multiple bonds, only one bond will be a sigma bond and the rest will be pi bonds. Ethyne has three bonds. Hence, ethyne has also one sigma bond and two pi bonds.