IF magnesium sulfide reacts with oxygen in the air it will produce
magnesium oxide + sulfur (IV) oxide
Step-by-step explanation
magnesium sulfide burn in oxygen to produce magnesium oxide and sulfur (iv) oxide according to the equation below
2MgS +3O2 →2MgO +2SO2
that is 2 moles of MgS react with 3 moles of O2 to produce 2 moles of MgO and 2 moles of SO2