JEE Chemistry 2025 Question with Solution

Given: We must identify the alkane having two secondary hydrogens.

Find: Which option contains exactly two hydrogens attached to a secondary carbon.

A secondary hydrogen is a hydrogen attached to a carbon atom bonded to two other carbon atoms.

From the provided solution, the correct option is B.

The solution analysis states that among the given compounds, 2,2,3,3-Tetramethylpentane has two secondary hydrogens because the relevant carbon position is attached to two other carbons and hence bears two secondary hydrogens.

There is a source discrepancy: the option list shows 2,2,3-Tetramethylpentane, while the solution repeatedly concludes 2,2,3,3-Tetramethylpentane. Since the solution is the primary source and marks Option B as correct, the defensible answer is B.

Therefore, the correct option is B.

Given: We need the alkane with two secondary hydrogens.

Find: Which structure has a carbon bonded to two other carbons and carrying two hydrogens.

Check the options using the definition of secondary carbon:

1. 2,2,4,4-Tetramethylhexane: the solution states that carbons bearing hydrogens are not secondary in the required way, so it is rejected.
2. Option B: the solution identifies this option as the one containing two secondary hydrogens.
3. 4-Ethyl-3,4-dimethyloctane: the solution states that the branching pattern does not match the required count.
4. 2,2,4,5-Tetramethylheptane: the solution rejects this as well.

Hence, based on the provided working, Option B is the correct choice.

Note: The solution text names the compound as 2,2,3,3-Tetramethylpentane, whereas the listed options text says 2,2,3-Tetramethylpentane. This mismatch appears to be a source typo, but the solution unambiguously selects Option B.