Assertion : In the series Sc to Zn, the enthalpy of atomisation of zinc is the lowest.
Reason : Zinc has greater number of unpaired electrons.

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

Explanation

To solve the given question, we will analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "In the series Sc to Zn, the enthalpy of atomisation of zinc is the lowest."

- **Explanation**: The enthalpy of atomisation refers to the amount of energy required to convert one mole of a substance into its gaseous atoms. In the transition series from Scandium (Sc) to Zinc (Zn), the enthalpy of atomisation generally decreases as we move from Sc to Zn. This is because as we move across the period, the number of unpaired electrons decreases, leading to weaker metallic bonds.

### Step 2: Analyze the Reason
The reason states that "Zinc has a greater number of unpaired electrons."

- **Explanation**: To determine the number of unpaired electrons in zinc, we need to look at its electronic configuration. Zinc has the electronic configuration of [Ar] 3d^10 4s^2. In this configuration, all electrons in the 3d and 4s subshells are paired. Therefore, zinc has **zero** unpaired electrons.

### Step 3: Conclusion
- **Assertion**: True (the enthalpy of atomisation of zinc is indeed the lowest in the series from Sc to Zn).
- **Reason**: False (zinc does not have a greater number of unpaired electrons; it has none).

### Final Answer
The assertion is true, but the reason is false. Therefore, the correct answer is that the assertion is true and the reason is false.

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