Schiff’s reagent is used for the differentiation between:

Options

A. HCHO and `CH_(3)`CHO
B. `CH_(3)COCH_(3)` and `CH_(3)`CHO
C. `C_(6)H_(5) - CH_(2) - overset(O)overset(||)(C ) - CH_(3) and C_(6)H_(5) - overset(O)overset(||)(C ) - CH_(2)-CH_(3)`
D. HCHO and `C_(6)H_(5)`CHO

Answer

To solve the question regarding the differentiation between compounds using Schiff’s reagent, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Schiff's Reagent**:
- Schiff's reagent is primarily used to detect the presence of aldehydes and ketones. It is a colorimetric reagent that changes color upon reaction with these functional groups.

2. **Reactivity with Aldehydes**:
- When Schiff's reagent reacts with aliphatic aldehydes, it produces an immediate red or pink color. This indicates the presence of an aliphatic aldehyde.

3. **Reactivity with Ketones**:
- In the case of aliphatic ketones and aromatic aldehydes, Schiff's reagent does not produce an immediate color change. Instead, it takes some time for a pink color to appear, indicating a slower reaction.

4. **Reactivity with Aromatic Ketones**:
- Aromatic ketones do not react with Schiff's reagent at all; hence, no color change will be observed.

5. **Analyzing the Options**:
- **Option A**: HCHO (formaldehyde, an aliphatic aldehyde) and CS3CHO (another aliphatic aldehyde). Both will give an immediate pink color, so they cannot be differentiated using Schiff's reagent.
- **Option B**: CH3COCH3 (an aliphatic ketone) and an aromatic aldehyde. The ketone will take time to show a pink color, while the aromatic aldehyde will eventually show a pink color too, allowing differentiation.
- **Option C**: Two aromatic ketones. Neither will react with Schiff's reagent, so they cannot be differentiated.
- **Option D**: HCHO (an aliphatic aldehyde) and C6H5CHO (an aromatic aldehyde). The aliphatic aldehyde will show an immediate pink color, while the aromatic aldehyde will show a delayed pink color, allowing for differentiation.

6. **Conclusion**:
- Based on the analysis, Schiff's reagent can be used to differentiate between:
- Aliphatic aldehydes and aromatic aldehydes (Option D).
- Aliphatic ketones and aromatic aldehydes (Option B).
- Therefore, the correct answers are Options B and D.