The number of neutrons in the radioactive isotope of hydrogen is

Options

A. 2
B. 0
C. 1
D. 3

Answer

To find the number of neutrons in the radioactive isotope of hydrogen, follow these steps:

### Step-by-Step Solution:

1. **Identify the Isotopes of Hydrogen**:
- Hydrogen has three isotopes:
- Protium (¹H) - 1 proton, 0 neutrons
- Deuterium (²H) - 1 proton, 1 neutron
- Tritium (³H) - 1 proton, 2 neutrons (this is the radioactive isotope)

2. **Understand the Definitions**:
- **Atomic Number (Z)**: The number of protons in the nucleus of an atom. For hydrogen, Z = 1.
- **Mass Number (A)**: The total number of protons and neutrons in the nucleus. For tritium, A = 3.

3. **Use the Formula to Calculate Neutrons**:
- The number of neutrons (N) can be calculated using the formula:
\[ N = A - Z \]
- Here, for tritium:
- Mass number (A) = 3
- Atomic number (Z) = 1

4. **Substitute the Values**:
- Substitute the values into the formula:
\[ N = 3 - 1 = 2 \]

5. **Conclusion**:
- Therefore, the number of neutrons in the radioactive isotope of hydrogen (tritium) is 2.

### Final Answer:
The number of neutrons in the radioactive isotope of hydrogen is **2**.

---