Total number of carbon atoms present in steroid nucleus.

Options

A. 24
B. 17
C. 10
D. 20

Answer

To determine the total number of carbon atoms present in the steroid nucleus, we can follow these steps:

### Step 1: Understand the Structure of Steroids
Steroids have a characteristic structure that consists of four fused rings. These rings are typically made up of carbon atoms.

### Step 2: Identify the Rings in the Steroid Nucleus
In the steroid nucleus, there are:
- Three six-membered carbon rings (cyclohexane rings)
- One five-membered carbon ring (cyclopentane ring)

### Step 3: Draw the Structure of a Common Steroid
For this example, we can use the steroid gonan as a representative structure.

### Step 4: Count the Carbon Atoms
- Each six-membered ring contributes 6 carbon atoms. Since there are three six-membered rings:
- 3 rings × 6 carbon atoms = 18 carbon atoms from the six-membered rings.
- The five-membered ring contributes 5 carbon atoms.

### Step 5: Total Carbon Count
Now, we need to sum the carbon atoms from all the rings:
- Total from three six-membered rings = 18
- Total from one five-membered ring = 5
- Total carbon atoms = 18 + 5 = 23

However, since some carbon atoms are shared between the rings, we need to adjust our count. After considering the shared carbons, the total number of unique carbon atoms in the steroid nucleus is 17.

### Final Answer
The total number of carbon atoms present in the steroid nucleus is **17**.

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