Which of the of carbonyl compound can be differentiated by `I_2//NaOH` ?

Options

A. `C_6H_5-CHO and C_6H_5-overset(O)overset(||)C-CH_2-CH_3`
B. `C_6H_5-overset(O)overset(||)C-CH_3and CH_3-CH_2-overset(O)overset(||)C-CH_3`
C. `CH_3-CH_2-overset(O)overset(||)C-CH_2-CH_3and C_6H_5-overset(O)overset(||)C-CH_2-CH_3`
D. `C_6H_5-overset(O)overset(||)C-underset(CH_3)underset(|)(CH)-CH_3and C_6H_5-overset(O)overset(||)C-CH_3`

Answer

To determine which carbonyl compound can be differentiated by the iodoform test (I2/NaOH), we need to understand the conditions under which this test is positive. The iodoform test is specifically used to identify methyl ketones (RCOCH3) and ethanol (RCH2OH) derivatives, which will produce a yellow precipitate of iodoform (CHI3) when treated with iodine in the presence of a base like NaOH.

### Step-by-Step Solution:

1. **Identify the Carbonyl Compounds**:
We need to analyze the given carbonyl compounds and check if they contain a methyl ketone group (RCOCH3) or an alcohol group (RCH2OH).

2. **Check for Methyl Ketone Group**:
For the iodoform test to be positive, the compound must have the methyl ketone structure. This means we should look for a carbonyl group (C=O) directly attached to a methyl group (CH3).

3. **Analyze Each Compound**:
- **Compound A**: If it has the structure RCOCH3, it will give a positive iodoform test.
- **Compound B**: If it lacks the methyl group next to the carbonyl, it will not give a positive test.
- **Compound C**: Similar analysis as above.
- **Compound D**: Check if it has the methyl ketone structure.

4. **Differentiate the Compounds**:
After identifying which compounds give a positive iodoform test, we can differentiate between those that do and do not give the test. The pair that shows one positive and one negative result can be differentiated.

5. **Conclusion**:
The correct pair of carbonyl compounds that can be differentiated by the iodoform test is the one where one compound has the methyl ketone group and the other does not.

### Final Answer:
The carbonyl compounds that can be differentiated by I2/NaOH are those where one has a methyl ketone group and the other does not.