Answer: Groups 1 and 2.
- A Groups 1 and 2
- B Groups 1 to 12
- C Groups 17 and 18
- D Groups 13 to 18
Correct answer: A. Groups 1 and 2
Explanation: The s-block consists of Group 1 (alkali metals) and Group 2 (alkaline earth metals) whose outermost electron is in an s orbital.
Each s-block metal ion emits a characteristic flame colour because heating excites electrons to higher energy levels; light is emitted as they fall back, with the colour determined by the specific energy gap.
Concept context
Group 1 (alkali metals) and Group 2 (alkaline earth metals). Learn their reactions with water and air, important compounds like NaOH, Na₂CO₃, and CaCO₃, and anomalous behaviour of lithium and beryllium.