Q5 / 150 · MHT CET 2026 (15 April Shift 1) · Chemistry
Identify the alkali metal having the smallest atomic size from following.
- Correct answerASodium
- BPotassium
- CRubidium
- DCaesium
Solution
The alkali metals given in the options belong to Group 1 of the periodic table.
As we move down a group, the number of electron shells increases, which leads to an increase in atomic size.
The order of the given alkali metals from top to bottom in Group 1 is Sodium (Na), Potassium (K), Rubidium (Rb), and Caesium (Cs).
Therefore, the order of their atomic sizes is Na < K < Rb < Cs.
Among the given options, Sodium has the smallest atomic size.
Answer: Sodium
As we move down a group, the number of electron shells increases, which leads to an increase in atomic size.
The order of the given alkali metals from top to bottom in Group 1 is Sodium (Na), Potassium (K), Rubidium (Rb), and Caesium (Cs).
Therefore, the order of their atomic sizes is Na < K < Rb < Cs.
Among the given options, Sodium has the smallest atomic size.
Answer: Sodium
Hence, the correct answer is option: 'A'.