Answer: Mg reduces CO2 to C (2Mg + CO2 → 2MgO + C), so CO2 extinguishers fail on Mg fires.
- A Mg reduces CO2 to C (2Mg + CO2 → 2MgO + C), so CO2 extinguishers fail on Mg fires
- B Magnesium is actually less reactive than carbon toward oxygen as frequently observed in practice
- C Magnesium generally does not burn when exposed to CO2 in many documented cases
- D The reaction instead produces stable magnesium carbonate, MgCO3 according to conventional understanding
Correct answer: A. Mg reduces CO2 to C (2Mg + CO2 → 2MgO + C), so CO2 extinguishers fail on Mg fires
Explanation: Magnesium is a stronger reducing agent than carbon and burns even in CO2, which is why CO2 fire extinguishers cannot be used on Mg fires.
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.