Question

Which among the following compounds contains phantom atom?

• A. \(\text{CH}_3\text{COOH}\)
• B. \(\text{CH}_3\text{CH}_2\text{Cl}\)
• C. \(\text{CH}_3\text{CH}_2\text{NH}_2\)
• D. \(\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}\)

Hint:

Phantom atoms are commonly discussed in resonance-stabilised functional groups like carboxylic acids.

Answer 1

The Correct Option is A

Step 1: Understand phantom atom.
A phantom atom is an atom which is not shown explicitly in the molecular formula but is assumed to be present to complete valency, especially in resonance structures.
Step 2: Analyze acetic acid structure.
In acetic acid (\(\text{CH}_3\text{COOH}\)), resonance structures of the carboxyl group involve delocalisation of electrons, where one oxygen behaves as if a hydrogen is shared or shifted, giving rise to the concept of a phantom atom.
Step 3: Eliminate other options.
The other compounds do not show such resonance-induced phantom atom behaviour.
Step 4: Conclusion.
Hence, \(\text{CH}_3\text{COOH}\) contains a phantom atom.