Unit Test Review - COMBUSTION: PART 1

Consider the temperature versus time graph below. (Graph) At what temperature is the substance a heated gas? A: at 100°C B: below 0°C C: above 100°C D: between 0°C and 100°C

Answer: C above 100°C

A gaseous substance turns directly into a solid. Which term describes this change? A: deposition B: evaporation C: melting D: sublimation

Answer: A deposition

Which best characterizes a crystal? A: a number of high speed particles moving randomly B: a dense substance that is hard and incompressible C: a high-energy state of matter made up of a swirling, ionized gas D: a loose association of particles moving past one another

Answer: B a dense substance that is hard and incompressible

When a strip of magnesium metal is touched to a flame, a bright light and a whitish substance are produced. Why is the burning of magnesium considered a chemical change? A: because the metal reaches a high temperature B: because the metal begins to melt C: because a new substance is formed D: because the metal is malleable

Answer: C because a new substance is formed

Which is a postulate of the kinetic-molecular theory? A: Gas particles have a small volume relative to the spaces between them. B: Gas particles have a large volume relative to the spaces between them. C: Gas particles are very small in size and always move slowly. D: Gas particles are very large in size and always move slowly.

Answer: A Gas particles have a small volume relative to the spaces between them.

Which statement best compares the melting point of butane (C4H10) with that of octane (C8H18)? A: The melting points of both substances are identical. B: The melting point is higher for butane. C: The melting point is higher for octane. D: The comparison of melting points cannot be made.

Answer: C The melting point is higher for octane.

Which of these is an example of a physical change? A: sugar, when heated, producing carbon dioxide and water B: solid ice, when heated, turning into liquid water C: sodium, when exposed to chlorine, forming sodium chloride D: aluminum, when heated in air, forming aluminum oxide

Answer: B solid ice, when heated, turning into liquid water

Which statement describes a chemical property of water? A: It reacts with sodium metal. B: It has a melting point of 0°C. C: It has a density of about 1 g/mL. D: It is clear and colorless.

Answer: A It reacts with sodium metal.

Which is an aspect of the kinetic-molecular theory and can be used to explain the compressibility of plasmas? A: Particles move independently of one another and are widely spaced. B: Particle kinetic energy increases with increasing temperature. C: Particles exert no attractive or repulsive force on one another. D: Particles always move even when they have fixed positions.

Answer: A Particles move independently of one another and are widely spaced.

The diagrams show gases that are stored in two separate but similar containers. (Gas 1 and Gas 2 Pictures) If both gases are at the same temperature, which one has the greater pressure? A: gas 1 because the particles are moving much faster B: gas 1 because it has fewer particles that are close together C: gas 2 because it has more particles that are colliding D: gas 2 because the particles have more space between them

Answer: C gas 2 because it has more particles that are colliding

Which statement describes a limitation of the kinetic-molecular theory for a gas? A: The theory assumes that particles do not experience intermolecular forces. B: The theory states that pressure is inversely proportional to volume. C: The theory assumes that particles are in random and continuous motion. D: The theory states that pressure increases with temperature.

Answer: A The theory assumes that particles do not experience intermolecular forces.

The diagrams show the particles of a substance.(Picture Shown Here) Which statement best describes the process that the diagrams show? A: A solid loses kinetic energy to become a liquid and then becomes a gas. B: A solid gains kinetic energy to become a liquid and then becomes a gas. C: A gas loses kinetic energy to become a liquid and then becomes a solid. D: A gas gains kinetic energy to become a liquid and then becomes a solid.

Answer: B A solid gains kinetic energy to become a liquid and then becomes a gas.

Which statement describes an extensive property of matter? A: It changes with the color of a substance. B: It changes when a new substance is formed. C: It changes with the amount of sample that is present. D: It changes with the composition of a substance.

Answer: C It changes with the amount of sample that is present.

According to the kinetic-molecular theory, what happens to a liquid when it is transferred from one container to another? A: The volume and the shape stay the same. B: The volume increases to fill the new container, but the shape stays the same. C: The volume stays the same, but the shape changes to fit the new container. D: The volume and the shape change to fill the new container.

Answer: C The volume stays the same, but the shape changes to fit the new container.

Which sequence represents the relationship between pressure and volume of an ideal gas as explained by the kinetic-molecular theory? A: more gas particles more collisions higher pressure B: smaller volume crowded particles less collisions lower pressure C: smaller volume crowded particles more collisions higher pressure D: more gas particles more kinetic energy more volume higher pressure

Answer: C smaller volume crowded particles more collisions higher pressure