Question

How many methyl groups are present in n-hexadecyl trimethyl ammonium chloride?

• A. 3
• B. 4
• C. 14
• D. 6

Hint:

In long alkyl chains, carefully distinguish between methyl (\(\text{CH}_3\)) and methylene (\(\text{CH}_2\)) groups while counting.

Answer 1

The Correct Option is C

Step 1: Write the structure from the name.
n-Hexadecyl trimethyl ammonium chloride consists of one hexadecyl group \((\text{C}_{16}\text{H}_{33})\) attached to a quaternary ammonium ion along with three methyl groups.

Step 2: Count methyl groups in the hexadecyl chain.
The n-hexadecyl group has the structure: \[ \text{CH}_3-(\text{CH}_2)_{14}- \] This chain contains one terminal methyl group and 13 methylene groups.

Step 3: Add methyl groups from ammonium part.
Trimethyl ammonium contains three additional methyl groups.

Step 4: Total count.
Methyl groups from hexadecyl chain = 11
Methyl groups from trimethyl ammonium = 3
Total methyl groups = \(11 + 3 = 14\)

Step 5: Conclusion.
The total number of methyl groups present is 14.