Molecular formula `C_(4)H_(6)` have two position isomers A and B. both A and B isomer decolourised the bromine water. B release `H_(2)` gas with sodium metal but isomer a does not release `H_2` gas. Write IUPAC name of A and B

Answer

To solve the problem, we need to identify the two position isomers (A and B) of the molecular formula C₄H₆, analyze their properties, and determine their IUPAC names.

### Step 1: Determine the Degree of Unsaturation (DU)
The degree of unsaturation (DU) can be calculated using the formula:
\[ \text{DU} = C + 1 - \frac{H}{2} \]
Where:
- C = number of carbon atoms
- H = number of hydrogen atoms

For C₄H₆:
- C = 4
- H = 6

Substituting the values:
\[ \text{DU} = 4 + 1 - \frac{6}{2} = 4 + 1 - 3 = 2 \]

This indicates that the compound can have either two double bonds, one triple bond, or a ring structure.

### Step 2: Analyze the Properties of Isomers A and B
Both isomers A and B decolorize bromine water, indicating that they both contain unsaturation (double or triple bonds).

Isomer B releases H₂ gas with sodium metal, while isomer A does not. This suggests that isomer B has an acidic hydrogen that can be released, while isomer A does not.

### Step 3: Draw the Structures of Isomers A and B
1. **Isomer A**: Since it does not release H₂ gas, it likely has a triple bond between carbons.
- Structure: CH₃-C≡C-CH₃ (But-2-yne)

2. **Isomer B**: This isomer has an acidic hydrogen and likely has a double bond.
- Structure: CH₃-CH=CH-C≡H (But-1-yne)

### Step 4: Assign the IUPAC Names
1. **Isomer A**:
- Structure: CH₃-C≡C-CH₃
- IUPAC Name: But-2-yne

2. **Isomer B**:
- Structure: CH₃-CH=CH-C≡H
- IUPAC Name: But-1-yne

### Final Answer
- Isomer A: But-2-yne
- Isomer B: But-1-yne