Final answer:
To verify if a chemical equation is balanced, one must ensure that the number and type of atoms are the same on both sides of the equation, adhering to the law of conservation of matter.
Step-by-step explanation:
In order to determine if the chemical equation is balanced, one must check if there is the same number and type of each atom on both sides of the equation. The law of conservation of matter requires that mass be always conserved in chemical reactions, meaning that the total number of atoms of the reactants must be the same as the total number of atoms of the product. A balanced chemical equation will have equal numbers of atoms for each element on the reactant and product sides, and this can be achieved by placing appropriate coefficients before each compound to match the numbers of atoms across. Remember, coefficients must be the simplest whole number ratio.
To answer the question, if each element has the same number of atoms on both sides of the equation, then the equation is balanced, which corresponds to choices (a) and (c). However, if they are not equal, then the equation is not balanced, necessitating the use of coefficients to correct it (as described in options (b) and (d)). It is not appropriate to determine balance by the number of reactants compared to products or by comparing coefficients alone as those are unrelated to the actual atom count.