The number of `sigma`- and `pi`-bond in 5-oxohexanoic acid, respectively, is :

Options

A. 18,2
B. 18,1
C. 17,2
D. 17,1

Explanation

To determine the number of sigma (σ) and pi (π) bonds in 5-oxohexanoic acid, we will follow these steps:

### Step 1: Understand the Structure of 5-oxohexanoic Acid
5-oxohexanoic acid is a carboxylic acid with a ketone group. The name indicates that the compound has a total of 6 carbon atoms (hexanoic) and a ketone group (oxo) at the 5th position.

### Step 2: Draw the Structure
1. Start by drawing a straight chain of 6 carbon atoms.
2. At the 5th carbon, add a ketone group (C=O).
3. At the 6th carbon, add a carboxylic acid group (–COOH).

The structure can be represented as:
```
O
||
C-C-C-C-C-COOH
```

### Step 3: Count the Sigma Bonds
1. **C-C Sigma Bonds**: Count the single bonds between carbon atoms. There are 5 C-C bonds in the chain.
2. **C-H Sigma Bonds**: Count the hydrogen atoms attached to each carbon. The 1st, 2nd, 3rd, and 4th carbons will have 2 hydrogen atoms each, while the 5th carbon (attached to the ketone) will have 1 hydrogen, and the 6th carbon (attached to the carboxylic acid) will have no hydrogen. This gives us:
- 1st C: 2 H
- 2nd C: 2 H
- 3rd C: 2 H
- 4th C: 2 H
- 5th C: 1 H
- 6th C: 0 H
Total = 2 + 2 + 2 + 2 + 1 + 0 = 9 C-H sigma bonds.
3. **C-O Sigma Bonds**: There are 2 C-O bonds (one from the ketone and one from the carboxylic acid).
4. **OH Sigma Bond**: There is 1 OH bond in the carboxylic acid.

Adding these together:
- C-C sigma bonds: 5
- C-H sigma bonds: 9
- C-O sigma bonds: 2
- OH sigma bond: 1

Total σ bonds = 5 + 9 + 2 + 1 = 17 σ bonds.

### Step 4: Count the Pi Bonds
1. **C=O (from the ketone)**: There is 1 π bond from the ketone group.
2. **C=O (from the carboxylic acid)**: There is another π bond from the carboxylic acid.

Total π bonds = 1 + 1 = 2 π bonds.

### Final Answer
The number of sigma (σ) and pi (π) bonds in 5-oxohexanoic acid is:
- **Sigma bonds (σ)**: 17
- **Pi bonds (π)**: 2