Hydrogen can be prepared by

Options

A. Electrolysis of acidified water
B. Bosch's process
C. Lane's process
D. All of these

Answer

To prepare hydrogen gas, we can utilize several methods. Below is a step-by-step explanation of three methods for preparing hydrogen, along with hints for each step.

### Step-by-Step Solution:

1. **Electrolysis of Acidified Water**:
- In this method, we perform electrolysis on water that has been acidified (usually with sulfuric acid).
- **At the Anode**: Water is oxidized to produce oxygen gas:
\[ 2H_2O \rightarrow O_2 + 4H^+ + 4e^- \]
- **At the Cathode**: Water is reduced to produce hydrogen gas:
\[ 4H^+ + 4e^- \rightarrow 2H_2 \]
- Therefore, hydrogen gas (H₂) is produced at the cathode.

**Hint**: Remember that electrolysis involves breaking down water into its components using electricity, and hydrogen is generated at the cathode.

2. **Bosh Process**:
- This is a commercial method for producing hydrogen. It involves two main reactions:
- **First Reaction**: Carbon (from coal) reacts with steam at high temperature (around 1000°C) to produce carbon monoxide and hydrogen:
\[ C + H_2O \rightarrow CO + H_2 \]
- **Second Reaction**: The carbon monoxide produced is then reacted with more steam in the presence of a catalyst (like Fe₂O₃) to produce additional hydrogen and carbon dioxide:
\[ CO + H_2O \rightarrow H_2 + CO_2 \]
- After this, carbon dioxide is removed, leaving behind hydrogen gas.

**Hint**: The Bosh process is a two-step reaction that utilizes carbon and steam to generate hydrogen commercially.

3. **Lenz Method**:
- This method also produces hydrogen commercially. The reaction involves iron and water:
- The overall reaction can be simplified as:
\[ 3Fe + 4H_2O \rightarrow Fe_2O_3 + 4H_2 \]
- Here, iron reacts with water to produce iron oxide and hydrogen gas.

**Hint**: The Lenz method involves the reaction of iron with water, leading to the generation of hydrogen gas.

### Conclusion:
All three methods mentioned above can produce hydrogen gas. Therefore, the answer to the question "Hydrogen can be prepared by" is **Option 4: All of the above**.