Chemistry 2001 JAMB Past Questions - Question 44: The pair of organic compounds that are isomers is

Correct Answer

D

Explanation

Isomers are compounds that have the same molecular formula but different arrangements of atoms. There are different types of isomers, including structural isomers, geometric isomers, and stereoisomers.

For example, two common types of isomers are structural isomers and geometric isomers.

1. **Structural Isomers:** These isomers have the same molecular formula but differ in the way the atoms are connected or arranged. An example is butane and isobutane. Both have the molecular formula C4H10, but their structures are different.

  - **Butane:**
    \[
    \begin{aligned}
    &\text{H} - \text{C} - \text{C} - \text{C} - \text{C} - \text{H} \\
    &\quad | \\
    &\text{H}
    \end{aligned}
    \]

  - **Isobutane:**
    \[
    \begin{aligned}
    &\text{H} - \text{C} \\
    &\quad | \\
    &\text{H} - \text{C} - \text{C} - \text{H} \\
    &\quad | \\
    &\text{H}
    \end{aligned}
    \]

2. **Geometric Isomers:** These isomers have the same connectivity of atoms but differ in the spatial arrangement of atoms due to the presence of a double bond or a ring. An example is cis- and trans-isomers of a compound with a double bond.

  - **Cis-2-butene:**
    \[
    \begin{aligned}
    &\text{H} \\
    &| \\
    &\text{H} - \text{C} = \text{C} - \text{H} \\
    &\quad | \\
    &\text{H}
    \end{aligned}
    \]

  - **Trans-2-butene:**
    \[
    \begin{aligned}
    &\text{H} \\
    &| \\
    &\text{H} - \text{C} = \text{C} - \text{H} \\
    &\quad | \\
    &\text{H}
    \end{aligned}
    \]

Without specifying the type of isomerism or providing specific compounds, it's challenging to identify a particular pair of isomers. If you have a specific pair or type of isomerism in mind, please provide more details.