In the following questions a statement of assertion (A) is followed by a statement of reason ( R)
A: Ionization enthalpy decreases on moving down the group .
R: Force of attraction between nucleus and electrons decreases on moving down the group.

Options

A. If Both Assertion & Reason are true and the reason is the correct explanation of the assertion then mark (1) .
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion then mark (2)
C. If Assertion is true statement but Reason is false then mark (3)
D. If both Assertion and Reason are false statements then mark (4)

Answer

To analyze the given assertion (A) and reason (R), we will break down the concepts involved step by step.

### Step 1: Understanding Ionization Enthalpy
- **Definition**: Ionization enthalpy (or ionization energy) is the amount of energy required to remove the outermost electron from an isolated gaseous atom.
- **Importance**: A higher ionization enthalpy indicates that the outermost electron is held more tightly by the nucleus, while a lower ionization enthalpy suggests that the electron can be removed more easily.

**Hint**: Remember that ionization enthalpy is related to how strongly the nucleus attracts the outermost electron.

### Step 2: Analyzing the Assertion
- **Assertion (A)**: "Ionization enthalpy decreases on moving down the group."
- **Explanation**: As we move down a group in the periodic table, the atomic size increases due to the addition of electron shells. This means that the outermost electrons are further away from the nucleus.

**Hint**: Consider how the distance between the nucleus and the outermost electron affects the energy required to remove that electron.

### Step 3: Understanding the Reason
- **Reason (R)**: "Force of attraction between nucleus and electrons decreases on moving down the group."
- **Explanation**: As the atomic size increases, the distance between the nucleus and the outermost electron increases. This increased distance results in a weaker electrostatic attraction between the positively charged nucleus and the negatively charged outermost electron.

**Hint**: Think about how distance affects the strength of the force of attraction between charged particles.

### Step 4: Connecting Assertion and Reason
- The assertion states that ionization enthalpy decreases down the group, which is true because the outermost electrons are held less tightly due to increased distance from the nucleus.
- The reason provided explains why this occurs: the force of attraction between the nucleus and the outermost electrons decreases as we move down the group.

**Hint**: Check if the reason logically supports the assertion.

### Step 5: Conclusion
- Both the assertion and reason are correct.
- The reason provided is a valid explanation for the assertion.

**Final Answer**: Both assertion (A) and reason (R) are correct, and the reason is the correct explanation for the assertion.