Assertion: Radius of the ion is always smaller than the parent atom.
Reason: Ion is formed by the loss or gain of electrons by the parent atom.

Options

A. Both A and B true and R is the correct explanation A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states: "The radius of the ion is always smaller than the parent atom."

- **Explanation**: This statement is generally false. When an atom loses electrons to form a cation (positively charged ion), the radius typically decreases because the remaining electrons are drawn closer to the nucleus due to the increased effective nuclear charge. However, when an atom gains electrons to form an anion (negatively charged ion), the radius increases because the additional electrons repel each other and spread out more.

### Step 2: Understand the Reason
The reason states: "Ion is formed by the loss or gain of electrons by the parent atom."

- **Explanation**: This statement is true. Ions are indeed formed when atoms either lose or gain electrons. For example, sodium (Na) loses an electron to become Na⁺, and chlorine (Cl) gains an electron to become Cl⁻.

### Step 3: Conclusion
- Since the assertion is false and the reason is true, the correct answer to the question is that the assertion is incorrect, while the reason is correct.

### Final Answer:
- Assertion: False
- Reason: True