Step-by-step explanation:
Given;
Number of moles of the elements = 3.8moles
Molar mass of Gold = 196.966g/mol
Molar mass of Magnesium = 24.3g/mol
Molar mass of Tin = 118.710g/mol
Molar mass of Bromine = 79.904g/mol
Mass = number of moles x molar mass
Mass of Gold = 3.8 x 196.966 = 748.5g
Mass of Magnesium = 3.8 x 24.3 = 92.3g
Mass of Tin = 3.8 x 118.710 = 451.1g
Mass of Bromine = 3.8 x 79.904 = 303.6g