🟡 2.41: REVIEW: EXAM: UNIT 2: MATTER: 5D 5W S1 23: CHM

What does Diagram 1 represent?

• a. element
• b. mixture
• c. compound

What does Diagram 3 represent?

• a. element
• b. mixture
• c. compound

Which of the following is formed when two elements combine chemically?

• a. an atom
• b. a compound
• c. an electron

What is the smallest unit of a chemical compound that still has the properties of that compound?

• a. a nucleus
• b. a molecule
• c. an element
• d. an atom

10. In chemistry, the elements are

• a. Pure chemical substances containing only one type of atom
• b. Pure chemical substances containing two or more different types of atoms
• c. Substances which can be burnt in the presence of air
• d. Substances which do not react with other substances

13. Sulfur (S), oxygen (O2), water (H2O), and sodium chloride (NaCl) are all examples of pure substances. Which of the following describes all pure substances?

• a. A pure substance consists of only one type of element
• b. A pure substance has a definite chemical composition
• c. A pure substance cannot be broken down into simpler substances by physical means
• d.A pure substance is normally found as a solid at room temperature

14. Copper is an element that is used in electrical wires. What is the smallest unit of copper that still maintains the characteristics of copper?

• a. the atom
• b. the electron
• c. the nucleus
• d. the proton

16. A compound is

• a. A mixture of two or more substances
• b. A pure substance formed by the chemical combination of two or more elements
• c. Made up of molecules consisting of only one type of atom
• d. Formed when one substance is dissolved in another

18. A container is filled with 100 mL of water and placed in a freezer. The water in the container freezes at 0⁰C. A second container filled with 90 mL of water is placed in a second freezer. At what temperature does this second container of water freeze?

• a. -10⁰C
• b. -1⁰C
• c. 0⁰C
• d. 10⁰C

19. Below are four ball-and-stick models representing compounds. Which of these models best represents ammonia (NH3)?

• A.
• B.
• C.
• D.