HCHO `overset(Conc.NaOH)(rarr)` (x) + (y)
(i) Oxidation number of carbon changes from
(A) O to +1 and 0 to –2 (B) 0 to +1 and 0 to –1
(C) 0 to +2 and 0 to –2 (D) None
(ii) Given reactin is an example of

Options

A. oxidation
B. Reduction
C. both
D. None

Answer

To solve the given question, we need to analyze the reaction of formaldehyde (HCHO) with concentrated sodium hydroxide (NaOH) and determine the changes in the oxidation states of carbon, as well as identify the type of reaction taking place.

### Step-by-Step Solution:

1. **Identify the Reaction**:
- The reaction involves formaldehyde (HCHO) reacting with concentrated NaOH. This is known as the **Cannizzaro reaction**, which occurs in the absence of alpha-hydrogens.

2. **Products Formation**:
- In the Cannizzaro reaction, one molecule of formaldehyde is oxidized to form a carboxylic acid (sodium formate, HCOONa), and another molecule is reduced to form an alcohol (methanol, CH3OH).
- Therefore, the products (X and Y) are:
- X = Sodium formate (HCOONa)
- Y = Methanol (CH3OH)

3. **Determine Oxidation States**:
- **For Methanol (CH3OH)**:
- Let the oxidation state of carbon be \( x \).
- The equation based on the oxidation state is:
\[ x + 3(+1) + (-2) = 0 \implies x + 3 - 2 = 0 \implies x + 1 = 0 \implies x = -1 \]
- Thus, the oxidation state of carbon in methanol is **-1**.

- **For Sodium Formate (HCOONa)**:
- Let the oxidation state of carbon be \( y \).
- The equation based on the oxidation state is:
\[ y + 2(-2) + (+1) = 0 \implies y - 4 + 1 = 0 \implies y - 3 = 0 \implies y = +3 \]
- Thus, the oxidation state of carbon in sodium formate is **+1**.

4. **Change in Oxidation States**:
- The oxidation state of carbon changes from **0 in HCHO** to **+1 in sodium formate** (oxidation) and from **0 in HCHO** to **-1 in methanol** (reduction).
- Therefore, the changes are:
- From 0 to +1 (oxidation)
- From 0 to -1 (reduction)

5. **Conclusion**:
- The correct option for the change in oxidation number of carbon is:
- (B) 0 to +1 and 0 to -1.
- The reaction is an example of **Cannizzaro reaction**, which involves both oxidation and reduction processes.

### Final Answers:
(i) The oxidation number of carbon changes from **0 to +1 and 0 to -1** (Option B).
(ii) The given reaction is an example of the **Cannizzaro reaction**.