20 multiple-choice questions in College Board exam style. Each has four choices and a full explanation of why each option is right or wrong.
Always balance the equation first. An unbalanced equation gives a wrong mole ratio and ruins every downstream stoichiometry calculation.
Find the limiting reactant by moles, not grams. Convert both reactants to moles and divide by their coefficients before comparing.
Watch for spectator ions. If an ion shows up unchanged on both sides of a full ionic equation, it doesn't belong in the net ionic equation.
Read the explanations even when you got it right. Each one teaches a small fact that often returns in a different form on the exam.