4. What was the experimental basis for
determining that the nucleus occupies a very small
fraction of the volume of an atom?
A) Neutral particles are emitted when a sheet of
beryllium is bombarded with  particles.
B) Photographic plates exposed to uranium will
darken.
C) A cathode ray is attracted to a positivelycharged plate.
D) A majority of  particles will pass through a thin
metal sheet undeflected, while a small percentage
scatter wildly.
7. Why does knowledge of atomic number enable
us to deduce the number of electrons present in an
atom?
8. Why do all atoms of an element have the same
atomic number, although they may have different
mass numbers?
A) All atoms of an element have the same number
of neutrons, but may have different numbers of
protons.
B) All atoms of an element have the same number
of protons, but may have different numbers of
neutrons.
C) The sum of neutrons and protons is the same
for every atom of an element.
D) The sum of neutrons and electrons is the same
for every atom of an element.
9. What do we call atoms of the same elements
with different mass numbers?
10. What is the mass number of an iron atom that
has 28 neutrons?
11. Calculate the number of neutrons of 239Pu.
18. Which of the following is a difference between
metals and nonmetals?
21. Elements whose names end with ium are
usually metals; sodium is one example. Identify a
nonmetal whose name also ends with ium.
23. Group the following elements in pairs that you
would expect to show similar chemical properties:
K, F, P, Na, Cl, and N.
A) K/N; F/Na; Cl/N
B) K/Na; F/Cl; P/N
C) K/F; P/Na; Cl/N
D) K/P; F/Na; Cl/N
24. What is the difference between an atom and a
molecule?
A) A molecule has more electrons than an atom.
B) An atom is charged while a molecule is not.
C) A molecule is an aggregate of atoms, while an
atom, by definition, is a single particle.
D) A molecule is bigger than an atom.
25. How are allotropes different from isotopes?
26. NH4+ is an example of which of the following?
A) a monatomic cation
B) a monatomic anion
C) a polyatomic cation
D) a polyatomic anion
27. Which of the following is an element?
A) N2
B) NH3
C) NO
D) CO
28. Which of the following is a compound?
A) N2
B) H2
C) O3
D) SO2
29. Which of the following describes the molecule
SO2?
A) A diatomic molecule containing atoms of the
same element.
B) A diatomic molecule containing atoms of
different elements.
C) A polyatomic molecule containing atoms of the
same element.
31. What is the number of protons and electrons in
Na+?
32. What is the number of protons and electrons in
S2–?
33. What is the number of protons and electrons in
Mg2+?
35. Which of the following molecules contains two
elements in a ratio of 2:1?
A) NO
B) NCl3
C) N2O4
D) P4O6
36. Which compound has the same empirical
formula as C6H12O6?
A) C12H24O12
B) C3H3O3
C) CH2ON
D) CHO2
38. What is the empirical formula of C6H6?
39. What is the empirical formula of P4O10?
40. What is the empirical formula of N2O5?
41. What is the empirical formula of Na2S2O4?
42. What is the molecular formula of glycine, an
amino acid present in proteins?
44. Which of the following compounds is likely to
be molecular?
PbCl2
LiF
B2H6 KCl
45. Which of the following compounds is likely to
be ionic?
CH4
NaBr
CCl4
NF3
46. Which of the following compounds is named
potassium hydrogen phosphate?
KH2PO4
K2HPO4
K3PO4
47. Which of the following compounds is named
lithium carbonate?
Na2CO3
LiHCO3
LiCO
Li2CO3
48. What is the name of KMnO4?
50. What is the formula for ammonium sulfate?
51. What is the formula for calcium hydrogen
phosphate?
52. What is the formula for lead (II) carbonate?
53. What is the formula for copper (II) cyanide?
56. One isotope of a metallic element has mass
number 65 and 35 neutrons in the nucleus. The
cation derived from the isotope has 28 electrons.
What is the symbol for this cation?
A) Br–
B) Br2+
C) Tb2+
D) Zn2+
Use the following to answer questions 58-61:
ATOM OR ION OF ELEMENT
Number of electrons
A
B
C
D
E
F
G
5
10 18 28 36 5
9
Number of protons
5
7
19 30 35 5
9
Number of neutrons
5
7
20 36 46 6
10
58. Which of the species are neutral?
59. Which of the species are negatively charged?
60. Which of the species are positively charged?
62. What is wrong with or ambiguous about the
phrase “four molecules of NaCl”?
63. Which of the following are elements?
(a) SO2,
(b) S8,
(c) Cs,
(d) N2O5,
(e) O,
(f) O2,
(g) O3,
(h) CH4,
(i) KBr,
(j) S,
(k) P4,
(l) LiF
65. Why is magnesium chloride (MgCl2) not called
magnesium(II) chloride?
66. Some compounds are better known by their
common names than by their systematic chemical
names. What is the chemical formula of baking
soda?
68. Which elements are most likely to form ionic
compounds?
69. Which metallic elements are most likely to form
cations with different charges?
78. The formula for calcium oxide is CaO. What are
the formulas for magnesium oxide and strontium
oxide?
83. Fluorine reacts with hydrogen (H) and
deuterium (D) to form hydrogen fluoride (HF) and
deuterium fluoride (DF), where deuterium is an
isotope of hydrogen. If a given amount of fluorine
reacts with one gram of hydrogen, with how much
deuterium would the same amount of fluorine
react?
85. Predict the formula of a binary compound
formed from Sr and Cl.
87. Which of the following is an alkali metal whose
cation contains 36 electrons?