Structure S 1.1—Introduction to the particulate nature of matter

Which of the following statements best describes a compound? A) A substance that cannot be broken down into simpler substances. B) A mixture of two or more elements that can be separated by physical means. C) A substance formed when two or more elements are chemically bonded in a fixed ratio. D) A combination of elements that retains the properties of the individual elements.

• A substance that can be broken down into simpler substances.

• A mixture of elements that cannot be separated by physical means.

• A combination of elements that creates a new element with different properties.

• C) A substance formed when two or more elements are chemically bonded in a fixed ratio.

Which of the following methods would be most appropriate for separating a mixture of sand and salt? A) Distillation B) Filtration C) Chromatography D) Recrystallization

• B) Filtration

• C) Filtration under pressure

• D) Magnetic separation

• A) Evaporation

What is the primary difference between homogeneous and heterogeneous mixtures? A) Homogeneous mixtures can be separated by chemical means, while heterogeneous cannot. B) Homogeneous mixtures have a uniform composition, while heterogeneous mixtures do not. C) Heterogeneous mixtures are always solid, while homogeneous mixtures are always liquid. D) There is no difference; they are the same.

• B) Homogeneous mixtures have a uniform composition, while heterogeneous mixtures do not.

• C) Heterogeneous mixtures are always liquid, while homogeneous mixtures can be solid or gas.

• D) Homogeneous mixtures have distinct layers, while heterogeneous mixtures are uniform.

• A) Homogeneous mixtures can be separated by physical means, while heterogeneous cannot.

Which of the following is an example of a homogeneous mixture? A) Salad B) Air C) Soil D) Oil and water

• C) Sugar water

• D) Sand and gravel

• B) Air

• A) Fruit smoothie

What is the process called when a solid changes directly into a gas? A) Melting B) Sublimation C) Evaporation D) Condensation

• Fusion

• B) Sublimation

• Condensation

• Freezing

Which of the following best describes an element? A) A substance made of two or more different types of atoms. B) A pure substance that cannot be broken down into simpler substances. C) A combination of two or more compounds. D) A mixture of different substances.

• A substance that can be easily separated into its components.

• A type of compound formed by chemical reactions.

• A homogeneous mixture of two or more elements.

• B) A pure substance that cannot be broken down into simpler substances.

What is the term for the amount of space an object occupies? A) Mass B) Volume C) Density D) Weight

• D) Force

• A) Temperature

• B) Volume

• C) Pressure

Which of the following statements is true about physical changes? A) They alter the chemical composition of a substance. B) They do not change the chemical composition of a substance. C) They are irreversible. D) They always involve a change in temperature.

• They always change the state of matter.

• They can change the color of a substance.

• They involve a chemical reaction.

• B) They do not change the chemical composition of a substance.

What is the primary characteristic of a gas? A) It has a definite shape and volume. B) It has a definite volume but no definite shape. C) It has neither a definite shape nor a definite volume. D) It has a definite shape but no definite volume.

• C) It has neither a definite shape nor a definite volume.

• G) It has a definite volume and can be compressed into a smaller space.

• F) It has a definite shape and can expand to fill a container.

• E) It has a definite shape and volume but can change state.

Which of the following is a characteristic of ionic compounds? A) They have low melting and boiling points. B) They conduct electricity in solid form. C) They are formed by the transfer of electrons. D) They are usually gases at room temperature.

• They have high melting and boiling points.

• They do not conduct electricity in any form.

• C) They are formed by the transfer of electrons.

• They are formed by the sharing of electrons.