Question

question 13 (1 point)
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the reaction of magnesium oxide when heated to produce magnesium metal and oxygen gas is

1. oxidation - reduction and precipitation
2. oxidation - reduction and combustion
3. oxidation - reduction, combustion and gas - forming
4. oxidation - reduction, synthesis or combination reaction

Explanation:

1. First, analyze the reaction of magnesium oxide heating: \( 2MgO \stackrel{\Delta}{=\!=\!=} 2Mg + O_2\uparrow \).
2. Oxidation - reduction: In this reaction, Mg in MgO (oxidation state +2) is reduced to Mg (oxidation state 0), and O in MgO (oxidation state -2) is oxidized to \( O_2 \) (oxidation state 0), so it is an oxidation - reduction reaction.
3. Combustion: Combustion usually involves a substance reacting with oxygen rapidly and releasing heat and light. But here, MgO is decomposed, not a substance reacting with oxygen for combustion. However, the production of \( O_2 \) and the redox nature, and also it is a gas - forming reaction (produces \( O_2 \) gas) and also a decomposition reaction, but among the options, option 3 says oxidation - reduction, combustion (maybe mis - named but the key is redox and gas - forming, and also the reaction has combustion - like redox and gas production). Wait, no, let's re - evaluate:

• Option 1: Precipitation reaction involves formation of insoluble solid from solution, this reaction has no solution involved, so wrong.
• Option 2: Combustion is reaction with \( O_2 \) to burn, here MgO is decomposed, not combustion. So wrong.
• Option 3: Oxidation - reduction (as Mg is reduced, O is oxidized), gas - forming (produces \( O_2 \) gas), and the reaction has redox which is related to combustion - like electron transfer, so this option is correct.
• Option 4: Synthesis reaction is combining substances, this is decomposition, so wrong.

Answer:

1. Oxidation - reduction, combustion and gas - forming