Alkane can be prepared by

Options

A. at action of Grignard's reagent with water
B. the reduction of alkyl halide with `H_2` in presence of nickel
C. the action of ethereal of alkyl halide with sodium metal
D. all the above

Answer

To prepare alkanes, several methods can be employed. Let's go through each method step by step.

### Step 1: Reaction of Grignard Reagent with Water
1. **Identify the Grignard Reagent**: A Grignard reagent is represented as R-Mg-X, where R is an alkyl group, Mg is magnesium, and X is a halogen.
- Example: Ethyl Magnesium Bromide (C2H5MgBr).

2. **React with Water**: When the Grignard reagent reacts with water (H2O), it behaves as a strong base.
- The reaction can be represented as:
\[ C2H5MgBr + H2O \rightarrow C2H6 + Mg(OH)Br \]
- Here, the alkyl group (C2H5) gains a hydrogen from water, forming ethane (C2H6), which is an alkane.

### Step 2: Reduction of Alkyl Halides
1. **Identify Alkyl Halide**: An alkyl halide is a compound with the general formula R-X, where R is an alkyl group and X is a halogen.
- Example: Reacting an alkyl halide like CH3CH2Br.

2. **Use of Hydrogen and Catalyst**: When the alkyl halide is treated with hydrogen gas (H2) in the presence of a catalyst (like nickel, Ni), a reduction occurs.
- The reaction can be represented as:
\[ CH3CH2Br + H2 \xrightarrow{Ni} CH3CH3 + HBr \]
- Here, ethane (C2H6) is produced, which is an alkane.

### Step 3: Wurtz Reaction
1. **React Alkyl Halide with Sodium**: In the Wurtz reaction, alkyl halides are treated with sodium metal (Na) in dry ether.
- Example: Reacting CH3CH2Cl with sodium.

2. **Formation of Alkanes**: The reaction leads to the coupling of two alkyl groups.
- The reaction can be represented as:
\[ 2 CH3CH2Cl + 2 Na \xrightarrow{dry\ ether} C4H10 + 2 NaCl \]
- Here, butane (C4H10) is formed, which is an alkane.

### Conclusion
From the above methods, we can conclude that alkanes can be prepared by:
1. Reaction of Grignard reagents with water.
2. Reduction of alkyl halides using hydrogen and a catalyst.
3. Wurtz reaction involving alkyl halides and sodium.

Thus, the answer to the question "Alkane can be prepared by" is **all of the above methods**.

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