Question

Which is the correct increasing order of atomic radii of Na, K, Mg, Rb ?

• A. Mg<K<Na<Rb
• B. Mg<Na<K<Rb
• C. Mg<Na<Rb<K
• D. Na<K<Rb<Mg

Hint:

Radius increases Down the group and Right to Left in a period.

Answer 1

The Correct Option is B

Step 1: Periodic Trends
- Across a period: Atomic radius decreases. - Down a group: Atomic radius increases.
Step 2: Positioning
- Period 3: Mg (Group 2), Na (Group 1). So, $\text{Mg}<\text{Na}$. - Group 1: Na, K, Rb. So, $\text{Na}<\text{K}<\text{Rb}$.
Step 3: Conclusion
Combining the trends: $\text{Mg}<\text{Na}<\text{K}<\text{Rb}$.
Final Answer: (B)