The ratio of moles of atoms in 12g of magnesium and 16g of sulphur will be:

Molar mass of magnesium = 24g

Given mass of magnesium = 12g


Number of moles = given mass of the element/ atomic weight of element


Number of moles of magnesium = 12/24 = 0.5 moles


Molar mass of sulphur = 32g


Given mass of sulphur = 16g


Number of moles = given mass of the element/ atomic weight of element


Number of moles of sulphur = 16/32 = 0.5 moles


Hence, 12 g of magnesium and 16 g of sulphur represents a mole ratio of 1 : 1

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