Answer
(a): $C_{8}H_{8} + 10O_{2} → 8CO_{2} + 4H_{2}O$
(b): $KOH + HCl → KCl + H_{2}O$
Work Step by Step
(a): Combustion of hydrocarbons produces carbon dioxide and water.
(b): Acid and base react to form salt and water.
Note that the same number of each of the elements must exist on the products and reactants side for each balanced reaction.
