A `underset(H_(2))overset(Pd//BaSO_(4))(rarr) ph-CHO underset((ii)H_(2)O)overset(SnCl_(2)//HCl)(larr)`B
A and B respectively are -

Options

A. Benzoyl chloride, benzonitrile
B. Benzyl chloride, benzylnitrile
C. Benzal chloride, benzonitrile
D. Benzotrichloride, benzonitrile

Answer

To solve the question, we need to identify the compounds A and B based on the given reactions.

### Step-by-Step Solution:

1. **Identify Compound A**:
- The first part of the reaction involves the transformation of a compound using hydrogen (H₂) in the presence of palladium (Pd) and barium sulfate (BaSO₄).
- This reaction is known as the Rosenmund reduction, which typically involves the reduction of an acid chloride to an aldehyde.
- The product of this reaction is given as ph-CHO, which is the structure of benzaldehyde (C₆H₅CHO).
- Therefore, the starting compound (A) must be benzoyl chloride (C₆H₅COCl), as it is the acid chloride that gets reduced to benzaldehyde.

2. **Identify Compound B**:
- The second part of the reaction involves the reduction of a nitrile (cyanobenzene or benzonitrile) using SnCl₂ in the presence of HCl and water (H₂O).
- The reaction converts the nitrile (C₆H₅CN) to an aldehyde (C₆H₅CHO), which is benzaldehyde.
- Therefore, the starting compound (B) is benzonitrile (C₆H₅CN).

### Final Answer:
- Compound A is **Benzoyl Chloride (C₆H₅COCl)**.
- Compound B is **Benzonitrile (C₆H₅CN)**.