Choose the correct answer for each question.

1. The nucleus of most atoms is made up of:

   1.   ?    protons and electrons
   2.   ?    protons and neutrons
   3.   ?    neutrons and electrons
   4.   ?    electrons and protons

2. The charge and mass number of an electron are:

   1.   ?    charge = +1, Mass number = 0
   2.   ?    charge = -1, Mass number = 0
   3.   ?    charge = 0, Mass number = 1
   4.   ?    charge = +1, Mass number = 1

3. The charge and mass number of a proton are:

   1.   ?    charge = +1, Mass number = 0
   2.   ?    charge = -1, Mass number = 0
   3.   ?    charge = 0, Mass number = 1
   4.   ?    charge = +1, Mass number = 1

4. The charge and mass number of a neutron are:

   1.   ?    charge = +1, Mass number = 0
   2.   ?    charge = -1, Mass number = 0
   3.   ?    charge = 0, Mass number = 1
   4.   ?    charge = +1, Mass number = 1

5. Most of the mass of the atom can be found in the:

   1.   ?    electron cloud
   2.   ?    nucleus
   3.   ?    electrons
   4.   ?    charges

6. The atomic number of an element is equal to:

   1.   ?    the number of protons in the atom
   2.   ?    the number of neutrons in the atom
   3.   ?    the number of protons plus the number of neutrons
   4.   ?    the number of protons plus the number of electrons

7. The mass number of an atom is determined by:

   1.   ?    adding the protons and electrons
   2.   ?    adding the neutrons and electrons
   3.   ?    adding the neutrons and protons
   4.   ?    the number of protons only

8. The laws of electrostatics consistently demonstrate that opposite charges:

   1.   ?    destroy one another
   2.   ?    attract
   3.   ?    repel

9. The laws of electrostatics consistently demonstrate that "like" (identical) charges:

   1.   ?    destroy one another
   2.   ?    attract
   3.   ?    repel

10. The _______________ constitute(s) most of the volume of an atom.

    1.   ?    protons
    2.   ?    neutrons
    3.   ?    nucleus
    4.   ?    electron cloud

11. Which of the following descriptions apply to the nucleus?

    1. Dense
    2. Mostly empty space
    3. Positively charged
    4. Small
    Check

12. Of the basic atomic particles, the one that would be attracted to a negatively charged metallic plate is the:

    1.   ?    proton
    2.   ?    neutron
    3.   ?    electron

13. The nucleus of the atom is held together by:

    1.   ?    electrons
    2.   ?    nuclear forces
    3.   ?    magnetism
    4.   ?    electrostatic attraction

14. Isotopes (such as hydrogen-1, hydrogen-2, and hydrogen-3) are atoms of the same element that differ in:

    1. the number of protons in the nucleus
    2. the number of electrons
    3. the number of neutrons in the nucleus
    4. the atomic number
    5. the mass number
    Check

15. 
    The letter "X" in the diagram above marks the:

    1. Electron cloud
    2. Location of the protons
    3. Nucleus
    4. Location of the neutrons
    5. Region of greatest density
    Check

16. 
    The letter "Y" in the diagram above marks the:

    1. Electron cloud
    2. Location of the protons
    3. Nucleus
    4. Location of the neutrons
    5. Region of greatest density
    Check

17. 
    The region labeled "X" in the diagram has a charge that is:

    1.   ?    positive
    2.   ?    negative
    3.   ?    neutral

18. 
    The region labeled "Y" in the diagram has a charge that is:

    1.   ?    positive
    2.   ?    negative
    3.   ?    neutral