Question
In period 4 of the periodic table, the elements with highest and lowest atomic radii are respectively.
JEE Main
Chemistry
Classification of Elements and Periodicity in Properties
2026
JEE Main 2026 (28 January Shift 1)
JEE Main Chemistry Question (2026) — Solution
Options
- A. Rb & Br
- B. K & Se
- C. K ~\&~ Br
- D. Na ~\&~ Cl
Answer
C. K ~\&~ Br
Step-by-step solution
In period 4, atomic radii decrease from left to right as nuclear charge increases while electron shell remains constant. K (potassium) is at the extreme left of period 4 metals and has the highest atomic radius. Br (bromine) is near the right end as a nonmetal and has the lowest atomic radius in this period. Therefore, the elements with highest and lowest atomic radii in period 4 are K and Br respectively.
Related: Chemistry — Classification of Elements and Periodicity in Properties · All PYQ Banks