Answer:
C.3
Step-by-step explanation:
The coefficient is the number of molecules needed for a set of reactions. The different reactions will have a different coefficient, so you have to balance the reaction first by knowing all the reactants and the product the reaction. The balanced reaction for sulfuric acid and aluminum hydroxide is:
2 Al(OH)3(s) + 3 H2SO4(aq) -----> Al2 (SO4)3(aq) + 6 H2O(l)
Every set of reactions will need 3 molecules of sulfuric acid and 2 molecules of aluminum hydroxide. The coefficient in front of sulfuric acid (H2SO4) is 3.