An atom which does not have any neutron is

Options

A. deutrium
B. tritium
C. helium
D. hydrogen

Explanation

To determine which atom does not have any neutrons, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Atomic Structure**:
- An atom consists of protons, neutrons, and electrons.
- The atomic number (Z) represents the number of protons in the nucleus.
- The mass number (A) is the total number of protons and neutrons in the nucleus.

2. **Formula for Neutrons**:
- The number of neutrons can be calculated using the formula:
\[ \text{Number of Neutrons} = A - Z \]
- Where A is the mass number and Z is the atomic number.

3. **Identify Atoms**:
- Let's consider the common isotopes of hydrogen:
- **Hydrogen (H)**:
- Atomic number (Z) = 1
- Mass number (A) = 1
- Neutrons = 1 - 1 = 0
- **Deuterium (D)**:
- Atomic number (Z) = 1
- Mass number (A) = 2
- Neutrons = 2 - 1 = 1
- **Tritium (T)**:
- Atomic number (Z) = 1
- Mass number (A) = 3
- Neutrons = 3 - 1 = 2

4. **Conclusion**:
- From the calculations, we see that only Hydrogen (H) has 0 neutrons. Therefore, the atom that does not have any neutrons is **Hydrogen**.

### Final Answer:
The atom which does not have any neutron is **Hydrogen (H)**.