A deuterium atom `:`

Options

A. has the same atomic mass as the hydrogen atom.
B. has the same electronic configuration as the hydrogen atom.
C. has the same composition of the nucleus as the hydrogen atom.
D. contains one proton more than a hydrogen atom.

Explanation

To solve the question regarding the properties of a deuterium atom compared to a hydrogen atom, let's analyze the statements provided step by step.

### Step-by-Step Solution:

1. **Identify the Symbols and Mass Numbers**:
- Deuterium is represented as \( ^2H \) or \( D \).
- Hydrogen is represented as \( ^1H \) or \( H \).

2. **Determine the Composition of Deuterium**:
- For deuterium (\( ^2H \)):
- Mass number = 2
- Number of protons = 1
- Number of neutrons = 1 (since mass number - number of protons = 2 - 1)
- Number of electrons = 1
- Therefore, the nuclear composition of deuterium is 1 proton and 1 neutron.

3. **Determine the Composition of Hydrogen**:
- For hydrogen (\( ^1H \)):
- Mass number = 1
- Number of protons = 1
- Number of neutrons = 0 (since mass number - number of protons = 1 - 1)
- Number of electrons = 1
- Therefore, the nuclear composition of hydrogen is 1 proton and 0 neutrons.

4. **Analyze the Statements**:
- **Statement A**: A deuterium atom has the same atomic mass as the hydrogen atom.
- **Analysis**: Incorrect, as deuterium has a mass number of 2 while hydrogen has a mass number of 1.

- **Statement B**: It has the same electronic configuration as the hydrogen atom.
- **Analysis**: Correct, both have the electronic configuration of \( 1s^1 \).

- **Statement C**: It has the same composition of the nucleus as the hydrogen atom.
- **Analysis**: Incorrect, deuterium has 1 neutron while hydrogen has none.

- **Statement D**: It contains one proton more than a hydrogen atom.
- **Analysis**: Incorrect, both have the same number of protons (1).

5. **Conclusion**:
- The only correct statement is **Statement B**: It has the same electronic configuration as the hydrogen atom.

### Final Answer:
The correct answer is **Statement B**.