1. Which of these is the largest?


            a. atom 

            b. molecule 

            c. electron 

            d. dalton

2. Water is called a polar molecule because ______.


            a. it has two ends 

            b. it easily comes apart

            c. many things dissolve in it 

            d. it has partial positive and partial negative regions

3. A pH of 5 is ______ than a pH of 7.


            a. two times more acidic 

            b. two times more basic

            c. 100 times more basic 

            d. 100 times more acidic

4. Covalent bonds occur when ___________.

            a. one atom gives an electron to another atom

            b. on atom gives a proton to another atom

            c. two atoms share electrons

            d. two atoms share protons

5. If an atom has 9 electrons, 9 protons, and 10 neutrons, its atomic number is _______.


            a. 9                              b. 10                                        c. 18                            d. 19

6. Whether an atom becomes an ion or not depends on ______.


            a. the number of neutrons in the nucleus 

            b. the number of protons in the nucleus

            c. the number of electrons in its outer shell 

            d. the number of electron shells it has

7. Isotopes, like carbon-12 and carbon-14, differ from each other in the number of _____ they have.


            a. electrons 

            b. neutrons 

            c. protons 

            d. electrons and protons

8. If you see a molecule of oxygen written as O = O it tells you that a molecule of oxygen ____.

            a. is formed by an ionic bond between two oxygen atoms

            b. is formed by each oxygen atom sharing one electron with the other oxygen

            c. is formed by each oxygen atom sharing two electrons with the other oxygen

            d. is formed by each oxygen atom sharing one proton with the other oxygen

9. The function of a buffer is to __________.


            a. prevent pH from changing 

            b. increase pH

            c. prevent enzymes from functioning 

            d. increase the rate at which enzymes work

10. Which of these is the strongest (most stable) bond?

            a. ionic bond

            b. hydrogen bond

            c. covalent bond

            d. all are the same strength