What is the number of carbon atoms which the palmitic acid and arachidonic acid contain (including carboxyl carbon )?

Options

A. 16,19
B. 15,19
C. 16, 20
D. 18,20

Answer

To determine the number of carbon atoms in palmitic acid and arachidonic acid, including the carboxyl carbon, we can follow these steps:

### Step 1: Identify the chemical formulas
- **Palmitic Acid**: The chemical formula is C16H32O2.
- **Arachidonic Acid**: The chemical formula is C20H32O2.

### Step 2: Count the carbon atoms
- For **Palmitic Acid**:
- The formula indicates there are 16 carbon atoms (C16).

- For **Arachidonic Acid**:
- The formula indicates there are 20 carbon atoms (C20).

### Step 3: Include the carboxyl carbon
- Both palmitic acid and arachidonic acid have a carboxyl group (-COOH) at one end of their structure. However, the carbon atoms counted in the formulas already include the carboxyl carbon. Therefore, we do not need to add any additional carbon atoms.

### Step 4: Summarize the total number of carbon atoms
- **Palmitic Acid**: 16 carbon atoms
- **Arachidonic Acid**: 20 carbon atoms

### Final Answer:
- The number of carbon atoms in palmitic acid is 16.
- The number of carbon atoms in arachidonic acid is 20.