`underset("donor")underset("Hydride")(RCHO) + underset("Acceptor")underset("Hydride")(R'CHO )rarr R-overset(O)overset(||)C-O^(Θ)+R'CH_(2)OH`
select the correct statement.

Options

A. Oxidation number of C in RCHO increases and that of `R'CHO` decreases.
B. Oxidation number of C in RCHO decreases and that of R'CHO increases.
C. Oxidation number of C remains unchanged in both but that of oxygen is affected.
D. In `CH_(3)CHO` and `C_(6)H_(5)CHO`, the former can act as RCHO (hydride donor).

Explanation

To solve the question regarding the reaction between RCHO and R'CHO, we need to analyze the process step by step. This reaction is indicative of the Cannizzaro reaction, where one aldehyde acts as a hydride donor and the other as a hydride acceptor.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have two aldehydes: RCHO (hydride donor) and R'CHO (hydride acceptor).
- Aldehydes are characterized by the functional group -CHO.

2. **Understand the Reaction**:
- In the Cannizzaro reaction, one aldehyde (RCHO) donates a hydride ion (H⁻) while the other aldehyde (R'CHO) accepts it.
- The product formed from the hydride donor (RCHO) is a carboxylate ion (RCOO⁻), and from the hydride acceptor (R'CHO), we get an alcohol (R'CH₂OH).

3. **Oxidation and Reduction**:
- The aldehyde that donates the hydride (RCHO) is oxidized, meaning its oxidation state increases.
- The aldehyde that accepts the hydride (R'CHO) is reduced, meaning its oxidation state decreases.

4. **Determine Oxidation States**:
- For RCHO, the carbon in the -CHO group goes from an oxidation state of +1 (in aldehyde) to +3 (in carboxylate ion).
- For R'CHO, the carbon in the -CHO group goes from an oxidation state of +1 (in aldehyde) to -1 (in alcohol).

5. **Conclusion**:
- The correct statement regarding the oxidation states is that the oxidation number of carbon in RCHO increases (as it is oxidized), while the oxidation number of carbon in R'CHO decreases (as it is reduced).
- Therefore, the correct answer is that the oxidation number of carbon in RCHO increases, and that of R'CHO decreases.

### Final Answer:
The correct statement is: "The oxidation number of carbon in RCHO increases while that of R'CHO decreases."