Which of the following molecular formula belongs to alkyne series ?

Options

A. `C_(7)H_(14)`
B. `C_(10)H_(22)`
C. `C_(9)H_(16)`
D. `C_(16)H_(32)`

Answer

To determine which molecular formula belongs to the alkyne series, we need to understand the general formulas for different types of hydrocarbons.

### Step-by-Step Solution:

1. **Identify the General Formulas**:
- **Alkane**: The general formula is \( C_nH_{2n+2} \).
- **Alkene**: The general formula is \( C_nH_{2n} \).
- **Alkyne**: The general formula is \( C_nH_{2n-2} \).

2. **Analyze Each Given Molecular Formula**:
- **Option 1: \( C_7H_{14} \)**:
- Here, \( n = 7 \).
- Calculate \( H \): \( H = 2n + 2 = 2(7) + 2 = 14 + 2 = 16 \).
- Since the number of hydrogens matches, this formula corresponds to an alkene.

- **Option 2: \( C_{10}H_{22} \)**:
- Here, \( n = 10 \).
- Calculate \( H \): \( H = 2n + 2 = 2(10) + 2 = 20 + 2 = 22 \).
- This formula corresponds to an alkane.

- **Option 3: \( C_9H_{16} \)**:
- Here, \( n = 9 \).
- Calculate \( H \): \( H = 2n - 2 = 2(9) - 2 = 18 - 2 = 16 \).
- Since the number of hydrogens matches, this formula corresponds to an alkyne.

- **Option 4: \( C_{16}H_{32} \)**:
- Here, \( n = 16 \).
- Calculate \( H \): \( H = 2n = 2(16) = 32 \).
- This formula corresponds to an alkane.

3. **Conclusion**:
- The only molecular formula that fits the alkyne series is **Option 3: \( C_9H_{16} \)**.

### Final Answer:
**The molecular formula that belongs to the alkyne series is \( C_9H_{16} \).**