Chemistry

Question Analysis
This question tests the student's understanding of the unique behavior of transition metals in terms of atomic radius across a period.

Key Concept Explanation
Transition metals show slight variations in atomic radius across a period due to the presence of d-electrons, which provide additional shielding and offset the effect of the increasing nuclear charge.

Step-by-step Solution
1. Consider the options provided.
2. Option A: Incorrect because the addition of new electron shells does not occur across a period; it occurs down a group.
3. Option B: Correct because d-electrons provide additional shielding, which slightly offsets the effect of the increasing nuclear charge.
4. Option C: Incorrect because the number of protons in...