1. Identify the element that does NOT belong to the same block as the other three:
- Thallium (Z = 81)
- Bismuth (Z = 83)
- Thorium (Z = 90)
- Polonium (Z = 84)
Show answer and explanation
Answer: (C) Thorium (Z = 90)
Thallium (Group 13), Bismuth (Group 15), and Polonium (Group 16) all belong to the p-block. Thorium (Z = 90) is an actinoid belonging to the f-block.