JEE Chemistry 2025 Question with Solution

Given: We must count how many of the listed molecules cannot give the iodoform reaction.

Find: The number of molecules that do not respond to the iodoform test, and hence the correct option.

The key requirement for the iodoform test is the presence of either $\mathrm{CH_3CO-}$ or $\mathrm{CH_3CH(OH)-}$, or a compound that can be oxidized to a methyl ketone.

From the extracted solution, the compounds identified as giving the iodoform test are:

• Ethanol
• Isopropyl alcohol
• Bromoacetone
• 2-Butanol
• 2-Butanone
• 2-Pentanone

The compounds identified there as not giving the iodoform test are:

• Butanal
• 3-Pentanone
• Pentanal
• 3-Pentanol

Thus, the number of molecules which cannot give the iodoform reaction is

Therefore, the correct option is B.

Given: The list contains Ethanol, Isopropyl alcohol, Bromoacetone, 2-Butanol, 2-Butanone, Butanal, 2-Pentanone, 3-Pentanone, Pentanal and 3-Pentanol.

Find: Which of these do not satisfy the structural requirement for the iodoform reaction.

Using the rule quoted in the solution, a compound gives the iodoform test if it contains a methyl ketone unit or is oxidized to one.

Classification stated across the solution:

1. Ethanol → gives iodoform test
2. Isopropyl alcohol → gives iodoform test
3. Bromoacetone → treated in Solution 1 as not giving under typical test context, but the page also marks option B as correct
4. 2-Butanol → gives iodoform test
5. 2-Butanone → gives iodoform test
6. Butanal → does not give iodoform test
7. 2-Pentanone → gives iodoform test in Solution 1, but Solution 2 lists it among non-givers
8. 3-Pentanone → does not give iodoform test
9. Pentanal → does not give iodoform test
10. 3-Pentanol → does not give iodoform test

The supplied the solution is internally inconsistent in the individual listing, but it explicitly states The Correct Option is B and concludes the count is

Hence, using the solution as primary source, the answer is B.