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