Assertion : In atomic form hydrogen consists of one proton and one electron.
Reason : In elemental form hydrogen exists as a diatomic molecule and is called dihydrogen.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that in atomic form, hydrogen consists of one proton and one electron.
- This is true because hydrogen (H) has an atomic number of 1, which means it has one proton in its nucleus.
- Since hydrogen is a neutral atom, the number of electrons must equal the number of protons, which is also one.

2. **Understanding the Reason:**
- The reason states that in elemental form, hydrogen exists as a diatomic molecule and is called dihydrogen (H₂).
- This is also true because hydrogen molecules (H₂) consist of two hydrogen atoms bonded together.
- Each hydrogen atom shares one electron with the other, forming a covalent bond, which results in a stable diatomic molecule.

3. **Evaluating the Relationship:**
- While both the assertion and the reason are true statements, the reason does not directly explain the assertion.
- The assertion is about the atomic structure of hydrogen, while the reason discusses its molecular form.
- Therefore, the reason does not serve as a correct explanation for the assertion.

4. **Conclusion:**
- Since both statements are true but the reason does not explain the assertion, the correct answer is that the assertion is true, the reason is true, but the reason is not the correct explanation for the assertion.

**Final Answer:**
- The correct option is (B): Assertion is true, Reason is true, but Reason is not the correct explanation for Assertion.

---