Q:1-An unknown element is found to contain 45 protons and an atomic mass of 64, what is its atomic number?
Mark one answer:
It cannot be determined.
19
45
64

Q:6-Which of the following statements about atoms is false?
Mark one answer:
Electrons do not orbit an atom’s nucleus; they exist in electron clouds surrounding the nucleus.
As each orbital of an atom is filled to capacity, electrons begin occupying a higher energy orbital.
Most of the volume of an atom is empty space.
Atoms are most stable when their outer electron shell (valence shell) is incomplete.

Q:7-What are isotopes?
Mark one answer:
Elements which have the same number of protons but a different number of neutrons.
Elements with the same atomic number but different atomic mass numbers.
Elements which have a different number of protons than electrons.
Both A and B are correct.

Q:8-What is the charge on sodium in the compound NaCL ?
Mark one answer:
-1
0
+1
+2

Q:9-A student is observing a chemical reaction occurring with visible bubbling. The bubbling eventually stops. The student can see that some of the original reactants are still intact inside the beaker, so he knows that not all the reactant has been used up. Therefore, the student knows he is now observing:
Mark one answer:
A failed reaction.
Equilibrium.
A decrease in temperature.
A completed reaction.

Q:10-Which of the following is the atomic mass of an atom containing 31 protons 31 electrons and 37 neutrons?
Mark one answer:
62
68
70
99