Question

How many equivalent groups of hydrogen are there in 2,4-dimethylpentane?

a) 1
b) 2
c) 3
d) 4

Answer 1

There are three equivalent groups of hydrogen in 2,4-dimethylpentane: the terminal methyl group hydrogens, the hydrogens on the middle carbon, and the hydrogens on the non-terminal methyl groups.

Step-by-step explanation:

To determine the number of equivalent groups of hydrogen in 2,4-dimethylpentane, we need to analyze the molecule's structure and identify how many sets of hydrogen atoms are in equivalent chemical environments. In 2,4-dimethylpentane, the first and fifth carbon atoms each have three equivalent hydrogen atoms, the second and fourth carbons are quaternary (no hydrogens since they have two methyl groups and two other carbons attached), and the third (middle) carbon has two hydrogens that are in the same environment. Additionally, each methyl group has three equivalent hydrogen atoms.

Considering these points, the equivalent hydrogen groups are as follows:

• The hydrogen atoms on the first and fifth carbon atoms (terminal CH3 groups).
• The hydrogen atoms on the third carbon.
• The hydrogen atoms on each of the methyl groups attached to the second and fourth carbons.

Therefore, there are three sets of equivalent hydrogen atoms in 2,4-dimethylpentane: on the terminal methyl groups, on the carbon in the middle, and on the non-terminal methyl groups. Hence, the correct answer is c) 3.