Two isomeric Ketones, 3-pentanone and 2-pentanone can be distinguished by:

Options

A. `I_2//NaOH` only
B. `NaHSO_3` only
C. NaCN/HCl
D. Both A and B

Answer

To distinguish between the isomeric ketones 3-pentanone and 2-pentanone, we can follow these steps:

### Step 1: Identify the Structures
- **2-Pentanone**: The ketone group (C=O) is located at the second carbon of the pentane chain.
- **3-Pentanone**: The ketone group is located at the third carbon of the pentane chain.

### Step 2: Perform the Iodoform Test
- The iodoform test is specific for methyl ketones (ketones with a CH3CO- group).
- **2-Pentanone** has a methyl group adjacent to the carbonyl (C=O) group, which allows it to react with iodine in the presence of NaOH to form iodoform (CHI3).
- **3-Pentanone** does not have a methyl group adjacent to the carbonyl group, so it will not give a positive iodoform test.

### Step 3: Perform the Sodium Bisulfite Test
- Sodium bisulfite (NaHSO3) can react with aldehydes and methyl ketones to form bisulfite addition compounds.
- **2-Pentanone** will react with NaHSO3 to form a bisulfite addition compound.
- **3-Pentanone**, due to steric hindrance, will not react with NaHSO3.

### Conclusion
Based on the above tests:
- **2-Pentanone** will give a positive iodoform test and will react with NaHSO3.
- **3-Pentanone** will not give a positive iodoform test and will not react with NaHSO3.

Thus, the two isomeric ketones can be distinguished by the iodoform test and the sodium bisulfite test.