Assertion: Hg is the only metal which is liquid at `0^(@)C`.
Reason: It has very I.P. and weak metallic bond.

Options

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

Answer

To analyze the assertion and reason provided in the question, we will break down the information step by step.

### Step 1: Understanding the Assertion
The assertion states that "Hg (mercury) is the only metal which is liquid at 0°C."

- **Explanation**: Mercury is indeed unique among metals because it remains in a liquid state at room temperature (0°C). This property is due to its specific atomic structure and bonding characteristics.

### Step 2: Understanding the Reason
The reason given is that "it has very high ionization potential (I.P.) and weak metallic bond."

- **Explanation**:
- **High Ionization Potential**: Mercury has a high ionization potential, which means it requires a significant amount of energy to remove an electron from its outer shell. This is due to its electronic configuration, which includes fully filled d-orbitals (5d^10) and a stable electron configuration.
- **Weak Metallic Bond**: The weak metallic bonding in mercury is a consequence of its high ionization energy. The electrons in the outer shell are not as free to move, which leads to weaker metallic bonding compared to other metals. This weak bonding contributes to its low melting point.

### Step 3: Conclusion
Both the assertion and the reason are correct. The assertion is true because mercury is the only metal that is liquid at 0°C. The reason is also true as it explains why mercury has a high ionization potential and weak metallic bonds, which contribute to its liquid state at this temperature.

### Final Answer
Both the assertion and reason are true, and the reason correctly explains the assertion.

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