Answer: The correct answer is Option 4.
Explanation:
Law of conservation of mass states that mass can neither be created nor can be destroyed but it can only be transformed from one form to another form. This law also states that the total number of individual atoms on the reactant side will be equal to the total number of individual atoms on the product side.
Every balanced chemical equation follows law of conservation of mass.
For the given options:
Option 1: [tex]BaCl_2+H_2SO_4\rightarrow BaSO_4+HCl[/tex]
Here, number of chlorine and hydrogen atoms on the reactant and product side are not same. Thus, this equation is not balanced.
Option 2: [tex]Cl_2+NaBr\rightarrow NaCl+Br_2[/tex]
Here, number of chlorine and bromine atoms on the reactant and product side are not same. Thus, this equation is not balanced.
Option 3: [tex]2H_2+N_2\rightarrow 2NH_3[/tex]
Here, number of hydrogen atoms on the reactant and product side are not same. Thus, this equation is not balanced.
Option 4: [tex]2H_2+O_2\rightarrow 2H_2O[/tex]
Here, number of hydrogen and oxygen atoms on both the sides are same. Thus, it is a balanced equation.
Hence, the correct answer is Option 4.
