Answer: Mg reduces CO 2 to C (2Mg + CO 2 → 2MgO + C), so CO 2 extinguishers fail on Mg fires.
- A Mg reduces CO<sub>2</sub> to C (2Mg + CO<sub>2</sub> → 2MgO + C), so CO<sub>2</sub> 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 CO<sub>2</sub> in many documented cases
- D The reaction instead produces stable magnesium carbonate, MgCO<sub>3</sub> according to conventional understanding
Correct answer: A. Mg reduces CO<sub>2</sub> to C (2Mg + CO<sub>2</sub> → 2MgO + C), so CO<sub>2</sub> extinguishers fail on Mg fires
Explanation: Magnesium is a stronger reducing agent than carbon and burns even in CO<sub>2</sub>, which is why CO<sub>2</sub> 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.