Which of the following reagents converts both acetaldehyde and acetone to alkanes?

Options

A. `Ni//H_(2)`
B. `LiAlH_(4)`
C. `I_(2)//NaOH`
D. Zn-hg/conc.HCl

Answer

To determine which reagent converts both acetaldehyde and acetone to alkanes, we can follow these steps:

### Step 1: Understand the Compounds
- **Acetaldehyde** (CH₃CHO) is an aldehyde.
- **Acetone** (CH₃COCH₃) is a ketone.

### Step 2: Identify the Reaction Type
- We are looking for a reduction reaction that converts carbonyl groups (C=O) in aldehydes and ketones to alkanes (C-C single bonds).

### Step 3: Recognize the Suitable Reagent
- The reagent that performs this conversion is **zinc amalgam (Zn/Hg)** in the presence of **concentrated hydrochloric acid (HCl)**. This combination is known for reducing carbonyl compounds.

### Step 4: Describe the Reaction
- This reaction is termed the **Clemenson reduction**. In this process:
- The carbonyl group (C=O) in acetaldehyde is reduced to a methylene group (–CH₂–), resulting in ethane (C₂H₆).
- The carbonyl group in acetone is also reduced to a methylene group, resulting in propane (C₃H₈).

### Step 5: Write the Chemical Equations
1. For acetaldehyde:
\[ \text{CH}_3\text{CHO} + \text{Zn/Hg} + \text{HCl} \rightarrow \text{C}_2\text{H}_6 \]
2. For acetone:
\[ \text{CH}_3\text{COCH}_3 + \text{Zn/Hg} + \text{HCl} \rightarrow \text{C}_3\text{H}_8 \]

### Conclusion
- The correct reagent that converts both acetaldehyde and acetone to alkanes is **zinc amalgam with concentrated hydrochloric acid**.

### Final Answer
- The answer is **Zinc amalgam with concentrated hydrochloric acid**.

---