Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group.
Reason (R): In a group, the atomic radial generally increases from top to bottom.
A
Both A and R are individually true and R is the correct explanation of A
B
Both A and R are individually true but R is NOT the correct explanation of A
C
A is true but R is false
D
A is false but R is true
Correct Answer: Option D
Explanation
1. This is an Assertion-Reason question about electron affinity trends in the periodic table.
2. Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group. This is false. Electron affinity generally *decreases* down a group because the added electron is further from the nucleus and shielded by more inner electrons, resulting in weaker attraction. There are exceptions, but the general trend is a decrease, not an increase.
3. Reason (R): In a group, the atomic radii generally increase from top to bottom. This is true. As we move down a group, electrons are added to higher principal energy levels, which are further from the nucleus, causing the atomic radii to increase.
4. Since Assertion (A) is false and Reason (R) is true, the correct option is (D).