Answer: Acetylene (C2H2) and Ca(OH)2.
- A Acetylene (C2H2) and Ca(OH)2
- B Ethylene and CaO in general practice
- C CO2 and Ca(OH)2 as frequently described
- D CO and CaCO3 in most textbook accounts
Correct answer: A. Acetylene (C2H2) and Ca(OH)2
Explanation: CaC2 + 2H2O → Ca(OH)2 + C2H2. This reaction was historically used to generate acetylene for lamps (carbide lamps).
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.