Which of the following ketone will not give yellow precipitate with `NaOH//I_(2)` ?

Options

A. 2-Pentanone
B. Benzophenone
C. Acetone
D. 2-Hexanone

Explanation

To determine which ketone will not give a yellow precipitate with NaOH/I2, we need to understand the conditions required for the iodoform reaction. The iodoform reaction occurs with carbonyl compounds that contain the acetyl group (CH3CO-). Let's analyze the given ketones step by step.

### Step 1: Identify the Ketones
We need to consider the structures of the ketones provided in the options. The options are:
1. 2-Pentanone
2. Acetone
3. 2-Hexanone
4. Benzophenone

### Step 2: Analyze Each Ketone for the Acetyl Group
- **2-Pentanone (CH3COCH2CH2CH3)**: This ketone has the acetyl group (CH3CO-). Therefore, it can undergo the iodoform reaction and will give a yellow precipitate.

- **Acetone (CH3COCH3)**: Acetone also contains the acetyl group (CH3CO-). Thus, it will undergo the iodoform reaction and produce a yellow precipitate.

- **2-Hexanone (CH3COCH2CH2CH2CH3)**: This ketone contains the acetyl group (CH3CO-). Therefore, it can also undergo the iodoform reaction and will yield a yellow precipitate.

- **Benzophenone (C6H5COC6H5)**: Benzophenone does not have an acetyl group (CH3CO-). It contains a phenyl group instead of a methyl group attached to the carbonyl. Therefore, benzophenone will not undergo the iodoform reaction and will not produce a yellow precipitate.

### Conclusion
The ketone that will not give a yellow precipitate with NaOH/I2 is **Benzophenone**.