Which of the following is mixed ketone?

Options

A. Pentanone
B. Acetophenone
C. Benzaphenone
D. Butanone

Answer

To determine which of the given options is a mixed ketone, we need to understand the definition and structure of mixed ketones. A mixed ketone has one side of the carbonyl group (C=O) as an alkyl group and the other side as an acyl group (which can be an aromatic or substituted aromatic group).

### Step-by-Step Solution:

1. **Identify the General Structure of Ketones**:
- Ketones have the general structure R1C(=O)R2, where R1 and R2 can be alkyl or acyl groups.
- A mixed ketone specifically has one alkyl group and one acyl group.

2. **Analyze Each Option**:
- **Option 1: Pentanone**:
- Structure: CH3-CH2-CH2-C(=O)-CH3
- Both R1 and R2 are alkyl groups (pentyl groups).
- **Conclusion**: This is a simple ketone, not a mixed ketone.

- **Option 2: Acetophenone**:
- Structure: C6H5-C(=O)-CH3
- One side has a methyl group (alkyl) and the other side has a phenyl group (acyl).
- **Conclusion**: This is a mixed ketone.

- **Option 3: Benzophenone**:
- Structure: C6H5-C(=O)-C6H5
- Both sides have phenyl groups (acyl groups).
- **Conclusion**: This is an aromatic ketone, not a mixed ketone.

- **Option 4: Butanone**:
- Structure: CH3-CH2-C(=O)-CH3
- Both sides have alkyl groups (butyl groups).
- **Conclusion**: This is a simple ketone, not a mixed ketone.

3. **Final Conclusion**:
- The only option that fits the definition of a mixed ketone is **acetophenone**.

### Final Answer:
**Acetophenone is the mixed ketone.**