Answer: Electrons jumping from excited states back to ground state emitting visible light.
- A Electrons jumping from excited states back to ground state emitting visible light
- B Small-scale nuclear reactions occurring within the heated metal according to standard textbooks
- C The colour of the gaseous combustion products formed in the flame in general practice
- D Simple ionic dissociation of the metal salt in the flame as frequently described
Correct answer: A. Electrons jumping from excited states back to ground state emitting visible light
Explanation: When atoms absorb flame energy, outer electrons are excited; on returning to ground state they emit characteristic spectral lines.
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.