Question

The simplest alkyne is:
A) \[{C_x}{H_{2x}}\]
B) \[{C_x}{H_{2x - 2}}\]
C) \[{C_x}{H_{2x - 4}}\]
D) \[{C_x}{H_{2x - 6}}\]

Answer 1

Hint: We have to remember that the hydrocarbons alkane, alkene and alkyne can be represented in straight chains or branched chains. The IUPAC name of these hydrocarbons can be named by using the suffix which is ane, ene and yne for alkane, alkene and alkyne respectively.

Complete answer:
We have to know that the alkanes, Alkenes and Alkynes are also known as hydrocarbons since they only contain carbon atoms and hydrogen atoms. Alkanes contain single bonds between carbon atoms thus they are known as unsaturated hydrocarbons whereas alkenes and alkynes contain double bond and triple bond thus they come under the category of saturated hydrocarbons. We look at all options to answer this question:
Option A) this is an incorrect option as \[{C_x}{H_{2x}}\] this is the simplest alkene. Alkene contains double bonds thus it is a saturated hydrocarbon. For example
\[{C_2}{H_4}\],this is the molecular formula for ethene molecules. The structure of the ethene molecule is shown below.

Ethene molecule contains two carbon atoms and four hydrogen atoms as shown in molecular as well as structural formula.
Option B) This is a correct option as \[{C_x}{H_{2x - 2}}\] this represents the simplest alkyne. Alkyne contains a triple bond thus it is a saturated hydrocarbon. For example
\[{C_2}{H_2}\], this is the molecular
Formula for acetylene molecule. The structure of the Acetylene molecule is shown below.

We have to know that the acetylene molecule contains two carbon atoms having triple bond and two hydrogen atoms which can be seen from molecular as well as structural formula.
Option C) this is an incorrect option.
Option D) this is an incorrect option.

Note:
We have to know that alkane is an unsaturated hydrocarbon having a single bond. We must remember that the simplest alkane is methane, which has one carbon atom and four hydrogen atoms. Molecular formula of methane is \[C{H_4}\].