Answer:

Step-by-step explanation:
Here,
for 1 mol of O₂, 2 moles of MgO are produced.
Also,
At STP:
1 mol of O₂ = 22.4 dm³/mol molar value
Moles in 242 L of O₂:
= volume / molar value
= 242 / 22.4
= 10.8 mol
Since:
1 mol of O₂ = 2 moles of MgO
10.8 mol of O₂ = 2 × 10.8 moles of Mgo
10.8 moles of O₂ = 21.6 moles of MgO
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