Final answer:
To balance a chemical equation, make sure the number of atoms of each element is the same on both sides. The given equations a), b), and c) are balanced.
Step-by-step explanation:
Chemical equations need to be balanced to satisfy the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction. To balance an equation, you need to make sure that the number of atoms of each element is the same on both sides of the equation.
a) 2Na(s) + O₂(g) → 2Na₂O(s) is balanced because there are 4 sodium atoms and 4 oxygen atoms on both sides. b) CH4(g) + 2O2(g) → CO₂(g) + 2H₂O(l) is balanced because there is 1 carbon atom, 4 hydrogen atoms, and 4 oxygen atoms on both sides. c) AgNO3(aq) + 2KCl(aq) → AgCl(s) + KNO3(aq) is balanced because there is 1 silver atom, 1 nitrogen atom, 3 oxygen atoms, 2 potassium atoms, and 2 chloride atoms on both sides.