Hydrogen reacts with ethene by `200^(@)-300^(@)C` to form ethane

Options

A. In the presence of catalyst
B. when their mixture is passed over Nl powder
C. when they are compressed to 20 atm
D. when both are at atmospheric pressure

Explanation

To solve the problem of how hydrogen reacts with ethene to form ethane, we can break down the reaction into clear steps:

### Step 1: Understand the Reactants and Products
- **Reactants**: Ethene (C₂H₄) and Hydrogen (H₂)
- **Product**: Ethane (C₂H₆)

### Step 2: Identify the Reaction Conditions
- The reaction occurs at a temperature range of **200°C to 300°C**.
- A **catalyst** is required for the reaction to proceed efficiently. In this case, **nickel powder** is used as the catalyst.

### Step 3: Write the Reaction Equation
The reaction can be represented by the following equation:
\[ \text{C}_2\text{H}_4 + \text{H}_2 \xrightarrow{\text{Ni, 200-300°C} } \text{C}_2\text{H}_6 \]

### Step 4: Explain the Mechanism
- Ethene is an unsaturated hydrocarbon (alkene) that contains a double bond.
- When hydrogen is added in the presence of a nickel catalyst, the double bond in ethene breaks.
- Hydrogen atoms add across the double bond, resulting in the formation of ethane, which is a saturated hydrocarbon (alkane).

### Step 5: Conclusion
The reaction of hydrogen with ethene to form ethane occurs under the specified conditions of temperature and in the presence of a nickel catalyst.

### Final Answer
The correct condition for the reaction to occur is when the mixture is passed over **nickel powder**.

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