Question

An unsaturated hydrocarbon having triple covalent bond and has 50 hydrogen atoms. The number of carbon atoms in its molecule will be ____

• A. $24$
• B. $25$
• C. $26$
• D. $28$

Answer 1

The correct option is C

$26$

Explanation for correct option:

(C) $26$

Hydrocarbon

• Hydrocarbons are a class of organic compounds composed only of carbon $\left(\mathrm{C}\right)$ and hydrogen$\left(\mathrm{H}\right)$ atoms.
• For example: Methane $\left({\mathrm{CH}}_4\right)$, Ethane$\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$.

Unsaturated hydrocarbon

• Unsaturated hydrocarbons are those that have double$\left(=\right)$ or triple$\left(\equiv \right)$ bonds between adjacent carbon atoms.
• Alkenes are the unsaturated hydrocarbons that contain carbon-carbon double bond.
• Alkynes are the unsaturated hydrocarbons that contain carbon-carbon triple bond.

The general formula for unsaturated hydrocarbons having triple bond is ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}-2}$. Here, $\mathrm{n}$ is the number of carbon atoms.

• If the number of hydrogen atoms is 50, then the number of carbon atoms is calculated as:

$$\begin{gathered} 2\mathrm{n}-2=50 \\ 2\mathrm{n}=52 \\ \mathrm{n}=26 \end{gathered}$$

Therefore, the correct option is (C). The number of carbon atoms in its molecule will be 26.