Final answer:
The chemical equation 4FeS + 7O2 → 2Fe2O3 + 4SO2 is balanced according to the law of conservation of mass and atoms, as the number of Fe, S, and O atoms is the same in both reactants and products.
Step-by-step explanation:
The student has presented the chemical equation 4FeS + 7O2 → 2Fe2O3 + 4SO2 and inquired about its balance status. To determine whether a chemical equation is balanced, we must ensure the number of atoms of each element on the reactant side equals the number on the product side, adhering to the law of conservation of mass and law of conservation of atoms.
By examining the chemical equation given:
There are 4 Fe atoms on both sides.
There are 4 S atoms on both sides.
There are 14 O atoms on both sides: 7 O2 molecules yield 14 O atoms, and in the products, each Fe2O3 contains 3 O atoms for a total of 6 O atoms, plus 4 SO2 each containing 2 O atoms gives another 8 O atoms. Together, that's 6 + 8 = 14 O atoms.
Since the number of atoms for each element is equal on both sides of the equation, the equation is indeed balanced. Therefore, option A is correct: It is balanced because the mass of the reactants is equal to the mass of the products. Remember, the balance of a chemical equation does not depend on the sum of the coefficients, so options C and D are incorrect regardless of their statements about coefficients, and option B is incorrect because it states that mass of the reactants is greater, which violates the conservation laws if the equation were unbalanced.