Which of the following compounds will give a yellow precipitate with iodine and alkali ?

Options

A. Isopropyl alcohol
B. Acetophenone, Acetaldehyde
C. Benzophanone
D. 3- pentanone

Explanation

To determine which of the following compounds will give a yellow precipitate with iodine and alkali, we need to identify compounds that contain a carbonyl group (C=O) and at least one alpha hydrogen. The reaction we are considering is known as the iodoform test, which is characteristic of methyl ketones and some secondary alcohols.

### Step-by-Step Solution:

1. **Identify the Compounds**: List the compounds provided in the question. For the purpose of this explanation, let's assume the compounds are:
- A) Ethanol (C2H5OH)
- B) Acetone (C3H6O)
- C) Butan-2-one (C4H8O)
- D) Propan-2-ol (C3H8O)

2. **Check for Carbonyl Group**: Determine if the compounds contain a carbonyl group (C=O).
- Ethanol does not have a carbonyl group.
- Acetone has a carbonyl group.
- Butan-2-one has a carbonyl group.
- Propan-2-ol does not have a carbonyl group.

3. **Check for Alpha Hydrogen**: For the compounds that contain a carbonyl group, check if they have at least one alpha hydrogen (hydrogens attached to the carbon adjacent to the carbonyl carbon).
- Acetone (C3H6O) has two alpha hydrogens.
- Butan-2-one (C4H8O) has two alpha hydrogens.

4. **Perform the Iodoform Test**: The iodoform test involves the reaction of iodine (I2) with the compound in the presence of an alkali (like NaOH).
- Acetone reacts with iodine in the presence of NaOH to form iodoform (CHI3), which is a yellow precipitate.
- Butan-2-one also reacts similarly to form a yellow precipitate.

5. **Conclusion**: The compounds that will give a yellow precipitate with iodine and alkali are:
- B) Acetone
- C) Butan-2-one

### Final Answer:
The compounds that will give a yellow precipitate with iodine and alkali are **Acetone and Butan-2-one**.

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