Which of the following is true in the periodic table?

Options

A. Atomic size increases from left to right across a period.
B. Electron affinity decreases on going down a group.
C. Metallic character decreases from left to right across a period.
D. Electronegativity increases on going down a group.

Explanation

To determine which statements are true regarding the periodic table, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Atomic size increases from left to right across a period.**
- **Analysis:** This statement is false. Atomic size actually decreases from left to right across a period. As we move across a period, protons are added to the nucleus, increasing the positive charge. Electrons are added to the same energy level, which results in a stronger attraction between the nucleus and the electrons, pulling them closer and decreasing the atomic radius.

2. **Statement 2: Electron affinity decreases on going down a group.**
- **Analysis:** This statement is true. As we move down a group in the periodic table, the atomic size increases because additional electron shells are added. This increased distance between the nucleus and the outermost electrons results in a weaker attraction for additional electrons, leading to a decrease in electron affinity.

3. **Statement 3: Metallic character decreases from left to right across a period.**
- **Analysis:** This statement is true. Metallic character is defined by the ability of an element to lose electrons. As we move from left to right across a period, elements become less metallic (more non-metallic) due to the increasing nuclear charge, which makes it harder for them to lose electrons.

4. **Statement 4: Electronegativity increases on going down a group.**
- **Analysis:** This statement is false. Electronegativity generally increases from left to right across a period and decreases down a group. As we move down a group, the increased distance of the outer electrons from the nucleus and the increased shielding effect reduce the ability of an atom to attract electrons in a bond.

### Conclusion:
- **True Statements:**
- Statement 2: Electron affinity decreases on going down a group.
- Statement 3: Metallic character decreases from left to right across a period.