Question

The Structural formula of Ethyne is
A.${\text{C}}{{\text{H}}_3}{\text{ - C }} \equiv {\text{ C - H}}$
B.${\text{H - C }} \equiv {\text{ C - H}}$
C.${{\text{H}}_2}{\text{ - C = C - }}{{\text{H}}_2}$
D. ${{\text{H}}_3}{\text{ - C - C - }}{{\text{H}}_3}$

Answer 1

Hint : We should read and understand the prefix and suffix of ethyne then only we can find the structural formula of ethyne. We must remember that the Ethyne, as the name suggests is an alkyne.

Complete step by step solution :
Alkynes are the unsaturated hydrocarbon containing at least one carbon-carbon triple bond between two carbon atoms. Well, there are three types of bonds in hydrocarbons which are single bond, the double bond, and triple bond and alkyne contain single and triple bonds.
Let’s see the molecular formula for alkynes which is ${C_n}{H_n}$.
So in the above question, there are two options with a triple bond in it. But we know that the prefix ‘eth’ means 2 carbons, so the only option with two carbons and a double bond is option B. ${\text{H - C }} \equiv {\text{ C - H}}$.

And hence option B is the correct answer.

Additional Information:
Alkane is a hydrocarbon that contains single bonds i.e. no double or triple bonds are being present in alkanes. It is denoted by the suffix –ane. The option D. ${{\text{H}}_3}{\text{ - C - C - }}{{\text{H}}_3}$is an alkane known as ethane.
Alkenes are the hydrocarbons with the presence of double bonds along with single bonds i.e. no triple bond is present. It is denoted by the suffix –ene. The option C. ${{\text{H}}_2}{\text{ - C = C - }}{{\text{H}}_2}$ is an alkene known as ethane.
In the case of the alkyne, an alkyne is a hydrocarbon with the presence of a triple bond i.e. triple bond is present.
Out of these three Alkanes are also known as saturated hydrocarbons and the other two are unsaturated hydrocarbons.
Alkanes are recognized by the suffix –ane and alkene are recognized by the suffix –ene.
Both the alkane and alkene have a molecular formula of the form ${C_n}{H_{2n + 2}}$ and ${C_n}{H_{2n}}$ respectively.

Note : We can also know that the smallest alkyne is acetylene which is called ethyne. Alkynes are hydrophobic in nature. Therefore, they dissolve well in an organic solvent but not in water. Alkynes are more reactive than usual hydrocarbons. For example, they are more reactive than alkenes in many reactions.