A student heats 25g of reactant ‘A’ with 50g of reactant ‘B’. He obtains 50g of product ‘C’ and recovers 25g of unreacted ‘B’. Which of the following law is confirmed in the following reaction?

Mass of A reacted = 25g                                                            Mass of B reacted = 50-25g=25g         Mass of C formed = 50gTherefore mass of A reacted +mass of B reacted =mass of C formed        Therefore law of conservation of mass is obeyed.Even though there is 50g of ‘B’, only 25g of ‘A’ is consumed, this illustrate that only specific amount of A and B combine which obey law of constant proportion.