GED and HiSET science — chemical reactions and the periodic table

Chemistry questions on the GED and HiSET science tests stay close to everyday life: a gas stove, a cold pack from a first-aid kit, a floor cleaner diluted in a bucket, rust in a damp garage. What they test is whether you can read the chemistry behind the situation — an equation, a concentration, a column of the periodic table — and reason with it. This material covers the physical-science chemistry that the tests draw on, with adult scenarios throughout.

The quiz starts with chemical equations. You identify the reactants and products in the burning of methane (CH₄ + 2O₂ → CO₂ + 2H₂O), count atoms using both coefficients and subscripts (how many oxygen atoms are in 3CO₂), and find the coefficient that balances the making of ammonia (N₂ + 3H₂ → 2NH₃). You apply conservation of mass to a reaction in a sealed flask, including the trap of a gas that forms but never leaves. You tell an endothermic process, such as an instant cold pack, from exothermic ones, and explain why fine steel wool rusts far faster than a solid bolt of the same mass: surface area, one of the factors — with temperature, concentration and catalysts — that control reaction rate. You identify the solvent and the solutes in a sports drink, compute the concentration of a cleaning solution after dilution, and predict what happens when more solute is added to a saturated solution. Finally you use the periodic table: elements in the same group, such as sodium and potassium, behave alike; noble gases are unreactive; and a compound such as carbon dioxide differs from an element and from a mixture.

The flashcards review reactants and products, coefficients and subscripts, conservation of mass, exothermic and endothermic reactions, catalysts, solutes and solvents, saturated solutions, noble gases and compounds.

The written work asks you to balance and explain equations, to set out a dilution calculation step by step, to explain a rate change with the particle idea of collisions, and to classify substances with reasons. In the oral exam an examiner presents chemistry you meet at home or at work, one question at a time, asks you to explain what is happening and why, and closes with brief feedback.

Chemical formulas are written with ordinary subscripts (H₂O, CO₂), as on the tests' screens. This is independent practice material based on the publicly described content of the two tests; it is not produced or endorsed by GED Testing Service or by ETS.

• Identify reactants and products and count atoms using coefficients and subscripts
• Balance simple chemical equations and apply conservation of mass
• Distinguish exothermic from endothermic processes from observations
• Explain how surface area, temperature, concentration and catalysts change reaction rate
• Identify solute and solvent and calculate concentration after dilution
• Use groups of the periodic table to predict similar properties and classify elements, compounds and mixtures

Practice material written by Zestly, based on the published descriptions of the GED Science test (ged.com) and the HiSET Science subtest (hiset.org: physical science — chemistry content).