A is your answer. it cant be B because H doesn't equal 2 on both sides.it cant be C because S doesn't equal 3 on both sides of the equation . It also cant be D because Au doesn't equal 3 on the first part of the equation so your best answer is A. Hope this helps!!!!
Explanation:
A balanced equation is defined as the equation where number of atoms of the reactant equal to the number of atoms of the product.
This also means that mass of the reactants is equal to the mass of products in a chemical equation.
For example, [tex]Au_{2}S_{3} + 3H_{2} \rightarrow 2Au + 3H_{2}S[/tex]
Here, number of atoms on reactant side are as follows.
Number of atoms on product side are as follows.
Hence, the number of atom of reactant side are equal to the number of atoms on product side.
Therefore, the reaction equation [tex]Au_{2}S_{3} + 3H_{2} \rightarrow 2Au + 3H_{2}S[/tex] is a balanced equation.
