An atom has 16 neutrons in its nucleus. The Atomic no. of the element is 15 the mass num­ ber of the element is

Options

A. 15
B. 16
C. 31
D. none of these

Answer

To find the mass number of the element with 16 neutrons and an atomic number of 15, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Atomic Number (Z)**: This is the number of protons in the nucleus of an atom. It also indicates the number of electrons in a neutral atom.
- **Mass Number (A)**: This is the total number of protons and neutrons in the nucleus of an atom.

2. **Identify Given Values**:
- The atomic number (Z) is given as 15.
- The number of neutrons is given as 16.

3. **Calculate the Number of Protons**:
- Since the atomic number (Z) is equal to the number of protons, we have:
\[ \text{Number of Protons} = Z = 15 \]

4. **Use the Mass Number Formula**:
- The mass number (A) can be calculated using the formula:
\[ A = \text{Number of Protons} + \text{Number of Neutrons} \]

5. **Substitute the Values**:
- Now substitute the values we have:
\[ A = 15 + 16 \]

6. **Perform the Calculation**:
- Adding the numbers gives:
\[ A = 31 \]

7. **Conclusion**:
- The mass number of the element is 31.

### Final Answer:
The mass number of the element is **31**.