Which one of the following is mixed ketone?

Options

A. `CH_(3)-overset(O)overset(||)(C)-CH_(3)`
B. `CH_(3)-CH_(2)-overset(O)overset(||)(C)-CH_(3)`
C. `C_(6)H_(5)-overset(O)overset(||)(C)-CH_(3)`
D. `CH_(3)-C_(6)H_(4)-overset(O)overset(||)(C)-C_(6)H_(5)`

Answer

To determine which of the given options is a mixed ketone, we need to understand the definitions of simple ketones and mixed ketones.

### Step-by-Step Solution:

1. **Define Ketones**: Ketones are organic compounds characterized by the presence of a carbonyl group (C=O) bonded to two carbon atoms (R1 and R2). The general structure can be represented as R1(C=O)R2.

2. **Identify Simple Ketones**:
- A simple ketone has both R1 and R2 as alkyl groups. For example, if R1 = CH3 (methyl) and R2 = C2H5 (ethyl), it is a simple ketone.
- If both R1 and R2 are acyl groups, it is also classified as a simple ketone.

3. **Identify Mixed Ketones**:
- A mixed ketone has one alkyl group and one acyl group. For example, if R1 = CH3 (methyl) and R2 = C6H5C(=O) (phenyl group), it is a mixed ketone.

4. **Analyze Given Options**:
- Examine each option to identify the nature of R1 and R2 in each case.
- If both R1 and R2 are alkyl groups, it is not a mixed ketone.
- If one is an alkyl group and the other is an acyl group, it qualifies as a mixed ketone.

5. **Select the Correct Option**:
- After analyzing the options, identify the one that has one alkyl group and one acyl group. This will be the mixed ketone.

6. **Conclusion**:
- Based on the analysis, the correct answer is the option where R1 is an alkyl group and R2 is an acyl group.

### Final Answer:
The correct option that represents a mixed ketone is option number three.