Answer: A) 30 grams
Step-by-step explanation: According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants.
mass of reactants= mass of antacid + mass of water= 30 g+ 50 g= 80 g
Given : Mass of product = 50 g
But mass of products should be equal to mass of reactants = 80 g
Thus mass of another product= (80-50)g = 30 g.