Number of sigma bonds in propyne will be

Options

A. 6
B. 7
C. 17
D. 16

Answer

To determine the number of sigma bonds in propyne (C₃H₄), we will follow these steps:

### Step 1: Write the molecular formula of propyne
Propyne is an alkyne with the molecular formula C₃H₄.

### Step 2: Draw the structure of propyne
Propyne has the following structure:
```
H H
| |
H--C≡C--C--H
| |
H H
```
In this structure, the first carbon (C1) is bonded to three hydrogens (H) and is connected to the second carbon (C2) via a triple bond. The second carbon (C2) is also connected to the third carbon (C3) via a single bond.

### Step 3: Identify and count the sigma bonds
- **Single Bonds**: Each single bond between carbon and hydrogen (C-H) is a sigma bond. There are 3 C-H bonds from C1 and 1 C-H bond from C3, totaling 4 sigma bonds from C-H.
- **Triple Bond**: The triple bond between C1 and C2 consists of 1 sigma bond and 2 pi bonds. So, we count 1 sigma bond from the triple bond.
- **Single Bond between C2 and C3**: The bond between C2 and C3 is a single bond, which is also a sigma bond.

### Step 4: Total the sigma bonds
Now, we can total the sigma bonds:
- From C-H bonds: 4 sigma bonds
- From C≡C bond: 1 sigma bond
- From C-C bond: 1 sigma bond

Total sigma bonds = 4 (C-H) + 1 (C≡C) + 1 (C-C) = 6 sigma bonds.

### Conclusion
The total number of sigma bonds in propyne is **6**.