In a hydrogen bomb, hydrogen is converted into
a. Barium b. Uranium-235
c. Uranium-238 d. Helium

Options

A. a. Barium
B. b. Uranium-235
C. c. Uranium-238
D. d. Helium

Explanation

To solve the question "In a hydrogen bomb, hydrogen is converted into," we need to analyze the nuclear reactions that occur in a hydrogen bomb, which primarily involve nuclear fusion.

### Step-by-Step Solution:

1. **Understanding Nuclear Fusion**:
- In a hydrogen bomb, the process that takes place is nuclear fusion. This is a reaction where two or more atomic nuclei combine to form a heavier nucleus, releasing a significant amount of energy in the process.

2. **Identifying the Reactants**:
- The primary reactants in a hydrogen bomb are isotopes of hydrogen, specifically deuterium (Hydrogen-2) and tritium (Hydrogen-3).

3. **Analyzing the Reactions**:
- The main reactions can be summarized as follows:
- **Reaction 1**:
\[ \text{Hydrogen-1} + \text{Hydrogen-1} \rightarrow \text{Helium-3} + \text{Neutron} \]
- **Reaction 2**:
\[ \text{Hydrogen-1} + \text{Hydrogen-1} \rightarrow \text{Tritium} + \text{Proton} \]
- **Reaction 3**:
\[ \text{Hydrogen-2} + \text{Hydrogen-3} \rightarrow \text{Helium-4} + \text{Neutron} \]

4. **Identifying the Products**:
- From the reactions above, we can see that the products of these fusion reactions include Helium (specifically Helium-4) and neutrons.

5. **Selecting the Correct Answer**:
- Given the options:
a. Barium
b. Uranium-235
c. Uranium-238
d. Helium
- The correct answer is **d. Helium**, as it is the product formed from the fusion of hydrogen isotopes in a hydrogen bomb.

### Final Answer:
The correct answer is **d. Helium**.