Which of the following pair of compounds react with bromine water?

Options

A. `CH_4 and C_2H_6`
B. `CH_4 and C_2H_4`
C. `C_2H_4 and C_2H_2`
D. None of these

Explanation

To determine which pair of compounds reacts with bromine water, we need to analyze the given compounds based on their saturation levels. Bromine water reacts with unsaturated hydrocarbons (alkenes and alkynes) but does not react with saturated hydrocarbons (alkanes).

### Step-by-Step Solution:

1. **Identify the Compounds:**
The given pairs of compounds are:
- Pair 1: CH4 (methane) and C2H6 (ethane)
- Pair 2: CH4 (methane) and C2H4 (ethylene)
- Pair 3: C2H4 (ethylene) and C2H2 (acetylene)

2. **Classify Each Compound:**
- **CH4 (Methane):** This is a saturated hydrocarbon (alkane).
- **C2H6 (Ethane):** This is also a saturated hydrocarbon (alkane).
- **C2H4 (Ethylene):** This is an unsaturated hydrocarbon (alkene).
- **C2H2 (Acetylene):** This is an unsaturated hydrocarbon (alkyne).

3. **Determine Reactivity with Bromine Water:**
- **Pair 1 (CH4 and C2H6):** Both are saturated hydrocarbons. **No reaction with bromine water.**
- **Pair 2 (CH4 and C2H4):** CH4 is saturated, and C2H4 is unsaturated. **Only C2H4 will react with bromine water.**
- **Pair 3 (C2H4 and C2H2):** Both are unsaturated hydrocarbons. **Both will react with bromine water.**

4. **Conclusion:**
The only pair that consists of compounds that will react with bromine water is **Pair 3: C2H4 (ethylene) and C2H2 (acetylene)**.

### Final Answer:
**The correct pair of compounds that react with bromine water is C2H4 and C2H2.**

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