In the given reaction `(A)+(B)overset(NaOH//Delta)rarrC_6H_5-CH=CH-CHO` A and B will be

Options

A. `C_6H_5 CHO and HCHO`
B. `C_6H_5CHO and CH_3CH_2-CHO`
C. `C_6H_5-CHO and CH_3-CHO`
D. `C_6H_5-CH_2-CHO and CH_3-CHO`

Answer

To solve the problem, we need to identify the compounds A and B that react in the presence of NaOH and heat to yield the product C6H5-CH=CH-CHO, which is an alpha, beta-unsaturated aldehyde.

### Step-by-Step Solution:

1. **Identify the Product Structure**:
The product given is C6H5-CH=CH-CHO. This indicates that the product has a benzene ring (C6H5), a double bond (CH=CH), and an aldehyde functional group (CHO).

2. **Understand the Reaction Type**:
The reaction involves NaOH and heat, which suggests that it is likely an aldol condensation reaction followed by dehydration. In aldol condensation, two aldehydes or one aldehyde and one ketone react to form a β-hydroxy aldehyde or ketone, which can then dehydrate to form an α,β-unsaturated carbonyl compound.

3. **Determine the Components A and B**:
- Since the product has a benzene ring, one of the reactants must be benzaldehyde (C6H5CHO).
- The other reactant must be an aldehyde that has at least two alpha hydrogens to facilitate the aldol reaction.

4. **Identify the Second Reactant**:
- The simplest aldehyde that meets the criteria of having at least two alpha hydrogens is acetaldehyde (CH3CHO).
- Acetaldehyde has two alpha hydrogens (the two hydrogens on the methyl group) and is a two-carbon aldehyde.

5. **Confirm the Reaction**:
- When benzaldehyde (A) and acetaldehyde (B) react under basic conditions (NaOH) and heat, they undergo aldol condensation to form a β-hydroxy aldehyde, which upon dehydration yields the final product C6H5-CH=CH-CHO.

6. **Final Answer**:
Therefore, the compounds A and B are:
- A: Benzaldehyde (C6H5CHO)
- B: Acetaldehyde (CH3CHO)