Question

Which among the following compounds is NOT a carbocyclic compound?

• A. Benzene
• B. Naphthalene
• C. Pyridine
• D. Cyclopentane

Hint:

"Carbo-" means carbon, and "-cyclic" means ring. If any element other than carbon (like the nitrogen atom in Pyridine) is built directly inside the ring loop, it immediately shifts out of carbocyclic into heterocyclic!

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We are given four cyclic organic compounds and must identify the single compound that does not qualify as a carbocyclic compound.

Step 2: Detailed Explanation:
Let's define the structural classifications of cyclic compounds:

• Carbocyclic Compounds (Homocyclic): Cyclic structures where the ring skeleton is composed entirely and exclusively of carbon atoms. Examples include Benzene ($\text{C}_6\text{H}_6$), Naphthalene ($\text{C}_{10}\text{H}_8$), and Cyclopentane ($\text{C}_5\text{H}_{10}$).

• Heterocyclic Compounds: Cyclic compounds where the ring contains at least one atom of an element other than carbon (known as a heteroatom, such as Nitrogen, Oxygen, or Sulfur) breaking up the carbon framework.

• Looking at Pyridine ($\text{C}_5\text{H}_5\text{N}$), its molecular structure consists of a six-membered aromatic ring resembling benzene, but with one of the CH groups replaced by a nitrogen atom. Because a nitrogen atom forms part of the ring framework itself, pyridine is classified as a heterocyclic compound, not a carbocyclic one.


Step 3: Final Answer: The compound that is not a carbocyclic compound is Pyridine, matching option (C).