Final answer:
The correct sequence of coefficients to balance the equation Mg(s)+O2(g) ⇒ 2MgO(s) is A. 1,1,2, which ensures an equal number of atoms on both sides.
Step-by-step explanation:
To balance the chemical equation Mg(s)+O2(g) ⇒ 2MgO(s), we need to ensure that the number of atoms of each element is the same on both sides of the equation. Given the choices A. 1,1,2 B. 3,1,2 C. 4,1,2 D. 2,1,2, the correct sequence of coefficients that will balance the equation is A. 1,1,2. This is because one magnesium atom on the reactant side will combine with one oxygen molecule (which contains two oxygen atoms) to form two units of magnesium oxide. Therefore, the equation will be balanced as 1 Mg + 1 O2 ⇒ 2 MgO, where both sides of the equation have one magnesium atom and two oxygen atoms.