Question

How many methyl groups are present in 2,5-Dimethyl-4-ethylnonane?
(A) 2
(B) 3
(C) 4
(D) 5

Answer 1

Hint :We know that methyl group is an alkyl derived from methane. Methyl group contains one carbon atom bonded to three hydrogen atoms. That is $ - C{H_3} $ . First we draw the structure of 2,5-Dimethyl-4-ethylnonane and then we count the number of methyl groups in it.

Complete step by step solution:
Given,
2,5-Dimethyl-4-ethylnonane.
Let’s draw the structure of 2,5-Dimethyl-4-ethylnonane.

(Count from right to left)
Now let’s count the number of methyl groups in it. That is $ - C{H_3} $ .

As we can see there are 5 methyl groups.
Hence the correct answer is option (d).

Note:
In above while writing the ethyl group (is an alkyl derived from ethane) we need to be careful. Just don’t write $ - {C_2}{H_5} $ it will give the wrong answer while counting the methyl group. Hence we write the ethyl group as $ - C{H_2} - C{H_3} $ .