Essential Chemistry Midterm Review: Key Concepts and Questions
School
Bellevue College**We aren't endorsed by this school
Course
CHEM 121
Subject
Chemistry
Date
Dec 12, 2024
Pages
4
Uploaded by SuperThunderBee55
Chemistry MidtermInstructions:Answer all questions. Choose the best answer for multiple-choice questions, mark True or False as needed, and provide clear answers for short-answer and diagram-related questions.Multiple Choice (Choose the correct option)1.What is the atomic number of an element?A. The number of protonsB. The number of neutronsC. The number of electrons in the outer shellD. The mass of the atomAnswer: A. The number of protons2.Which subatomic particle has a negative charge?A. ProtonB. NeutronC. ElectronD. QuarkAnswer: C. Electron3.What is the chemical formula for water?A. H₂B. O₂C. HO₂D. HO₂Answer: C. HO₂4.What is the pH of a neutral solution?A. 0B. 7C. 14D. 10Answer: B. 75.Which state of matter has a definite shape and volume?A. SolidB. LiquidC. GasD. Plasma
Answer: A. Solid6.Which type of bond involves the sharing of electrons?A. IonicB. CovalentC. MetallicD. HydrogenAnswer: B. Covalent7.What is Avogadro’s number?A. 6.022 × 10²³B. 3.14C. 9.81D. 1.67 × 10²⁷⁻Answer: A. 6.022 × 10²³8.What is the most electronegative element?A. HydrogenB. OxygenC. FluorineD. CarbonAnswer: C. Fluorine9.What does the periodic table primarily organize elements by?A. Atomic massB. Atomic numberC. Number of isotopesD. DensityAnswer: B. Atomic number10.What is the process of a liquid turning into a gas called?A. CondensationB. SublimationC. EvaporationD. DepositionAnswer: C. EvaporationTrue/False11.Isotopes of an element have the same number of protons but different numbers of neutrons.Answer: True
12.Ionic bonds form between two nonmetals.Answer: False13.Metals are good conductors of electricity.Answer: True14.An acid has a pH greater than 7.Answer: False15.The nucleus of an atom contains protons and electrons.Answer: False16.A catalyst speeds up a reaction without being consumed.Answer: True17.In a chemical reaction, reactants are on the right side of the equation.Answer: False18.The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction.Answer: True19.The boiling point of water is 100°C at standard atmospheric pressure.Answer: True20.A molecule of oxygen gas (O) contains a double bond.₂Answer: TrueShort Answer21.Define an isotope.Answer: An isotope is a variant of an element that has the same number ofprotons but a different number of neutrons in the nucleus.22.Write the chemical equation for the combustion of methane (CH₄).Answer: CH₄ + 2O₂ → CO₂ + 2H₂O23.Explain the difference between exothermic and endothermic reactions.Answer:●Exothermic reactions release heat energy into the surroundings.●Endothermic reactions absorb heat energy from the surroundings.24.What is the molar mass of water (HO)?₂Answer: The molar mass of HO is 18 g/mol (2 × 1 for hydrogen + 16 for ₂
oxygen).25.Describe the difference between a homogeneous and heterogeneous mixture.Answer:●A homogeneous mixture has a uniform composition throughout (e.g., salt water).●A heterogeneous mixture has distinct components that can be visibly separated (e.g., sand and water).