Which of the following statement is//are correct
(1) Hydrazone of an aklehyde when heated with sodium ethoxide forms alkane This is known as wolf-kishnec reaction.
(2) Cannizzaro's reaction is given by those aldehydes which do not have a-hydrogen atom.
(3) Two separate solution, Fehling's solution A `(CuSO_(4))` and Fehling's solution `B(NaOH+` roschell salt an at first mixed up together and is then heated with the aldehyde A CuO precipitate is formed.
(4) Tollen's reagent gives silver mirror with acetaldehyde.

Options

A. 1
B. 2
C. 3
D. 4

Answer

To determine which statements regarding aldehydes and their reactions are correct, we will analyze each statement one by one.

### Step 1: Analyze Statement 1
**Statement:** Hydrazone of an aldehyde when heated with sodium ethoxide forms alkene. This is known as Wolf-Kishner reaction.

**Analysis:**
- The Wolf-Kishner reduction involves the conversion of hydrazones into alkenes by heating with a strong base, typically sodium ethoxide or potassium hydroxide.
- The reaction mechanism involves the removal of nitrogen gas and the formation of an alkene.

**Conclusion:** This statement is correct.

### Step 2: Analyze Statement 2
**Statement:** Cannizzaro's reaction is given by those aldehydes which do not have α-hydrogen atoms.

**Analysis:**
- Cannizzaro's reaction occurs with aldehydes that lack α-hydrogens. In this reaction, one molecule of the aldehyde is oxidized to a carboxylic acid while another is reduced to an alcohol.
- A classic example is formaldehyde, which has no α-hydrogens.

**Conclusion:** This statement is correct.

### Step 3: Analyze Statement 3
**Statement:** Two separate solutions, Fehling's solution A (CuSO₄) and Fehling's solution B (NaOH + Rochelle salt), when mixed and heated with an aldehyde, form a CuO precipitate.

**Analysis:**
- Fehling's test involves the reduction of Cu²⁺ ions to Cu⁺ ions, forming a red precipitate of cuprous oxide (Cu₂O) when an aldehyde is present.
- The statement incorrectly states that a CuO precipitate is formed. Instead, it should state that a red precipitate of Cu₂O is formed.

**Conclusion:** This statement is incorrect.

### Step 4: Analyze Statement 4
**Statement:** Tollen's reagent gives a silver mirror with acetaldehyde.

**Analysis:**
- Tollen's reagent (ammoniacal silver nitrate) is used to test for aldehydes. It reduces aldehydes to their corresponding carboxylic acids while depositing metallic silver, resulting in a silver mirror.
- Acetaldehyde, being an aldehyde, will indeed give a positive silver mirror test.

**Conclusion:** This statement is correct.

### Final Conclusion:
The correct statements are:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect
- Statement 4: Correct

Thus, the correct options are **1, 2, and 4**.

### Summary of Correct Statements:
- **Correct Statements:** 1, 2, and 4
- **Incorrect Statement:** 3