An alkaloid contains 17.28% of nitrogen and its molecular mass is 162. The number of nitrogen atoms present in one molecule of the alkaloid is

Options

A. five
B. four
C. three
D. two

Answer

To determine the number of nitrogen atoms present in one molecule of the alkaloid, we can follow these steps:

### Step 1: Calculate the mass of nitrogen in one molecule of the alkaloid.
Given that the alkaloid contains 17.28% nitrogen and its molecular mass is 162 g/mol, we can find the mass of nitrogen in one molecule.

\[ \text{Mass of nitrogen} = \text{Molecular mass} \times \left(\frac{\text{Percentage of nitrogen}}{100}\right) \]

\[ \text{Mass of nitrogen} = 162 \, \text{g/mol} \times \left(\frac{17.28}{100}\right) = 162 \times 0.1728 = 28.0512 \, \text{g/mol} \]

### Step 2: Determine the number of nitrogen atoms in one molecule.
Next, we need to find out how many nitrogen atoms correspond to this mass. The atomic mass of nitrogen (N) is approximately 14 g/mol.

\[ \text{Number of nitrogen atoms} = \frac{\text{Mass of nitrogen}}{\text{Atomic mass of nitrogen}} \]

\[ \text{Number of nitrogen atoms} = \frac{28.0512 \, \text{g/mol}}{14 \, \text{g/mol}} = 2.0036 \]

Since the number of atoms must be a whole number, we round this to the nearest whole number, which is 2.

### Conclusion:
The number of nitrogen atoms present in one molecule of the alkaloid is **2**.

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