Chapter 2: Atoms, Molecules, and Ions

	1.	According to the law of definite proportions,
A)	the ratio of the masses of the elements in a compound is always the same.	
B)	it is not possible for the same two elements to form more than one compound.	
C)	if the same two elements form two different compounds, they do so in the same ratio.	
D)	the total mass after a chemical change is the same as before the change.	

ANS:	A	PTS:	1	DIF:	easy	TOP:	 2.2
KEY:	general chemistry | general concepts | matter | compound

	2.	Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?
A)	CaO and CaCl2	
B)	NO and NO2	
C)	H2O and HI	
D)	CH4 and CO2	
E)	NH3 and NBr3	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.2
KEY:	general chemistry | general concepts | matter | compound

	3.	How many of the following did Dalton not discuss in his atomic theory?
 I.	isotopes	
II.	ions	
III.	protons	
IV.	neutrons	
V.		electrons	

A)	2	
B)	5	
C)	4	
D)	1	
E)	3	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.3
KEY:	general chemistry | early atomic theory | atomic theory of matter | Dalton's atomic theory

	4.	When 3.0 L of hydrogen gas (H2) reacts with 1.0 L of nitrogen gas (N2), 2.0 L of gaseous product is formed. All volumes of gases are measured at the same temperature and pressure. What is the formula of the product?
A)	NH	
B)	NH4	
C)	N2H3	
D)	N3H	
E)	NH3	

ANS:	E	PTS:	1	DIF:	easy	TOP:	 2.4
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | molecular substance

	5.	Which one of the following statements about atomic structure is false?
A)	Almost all of the mass of the atom is concentrated in the nucleus.	
B)	The protons and neutrons in the nucleus are very tightly packed.	
C)	The number of protons and the number of neutrons are always the same in the neutral atom.	
D)	The electrons occupy a very large volume compared to the nucleus.	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.4 | 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | nuclear structure

	6.	Which of the experiments listed below did not provide the information stated about the nature of the atom?
A)	The Rutherford experiment proved that the Thomson "plum pudding" model of the atom was essentially correct.	
B)	The Rutherford experiment determined the charge on the nucleus.	
C)	The cathode-ray tube proved that electrons have a negative charge.	
D)	Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.	

ANS:	A	PTS:	1	DIF:	easy	TOP:	 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | structure of the atom

	7.	Which of the following atomic symbols is incorrect?
A)	3115P	
B)	2010Ne	
C)	3417Cl	
D)	3919K	
E)	136N	

ANS:	E	PTS:	1	DIF:	easy	TOP:	 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	8.	The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus
A)	75 protons, 110 neutrons.	
B)	75 protons, 75 neutrons.	
C)	75 protons, 130 neutrons.	
D)	130 protons, 75 neutrons.	
E)	not enough information is given.	

ANS:	A	PTS:	1	DIF:	easy	TOP:	 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	9.	Which of the following statements is(are) true?
 I.	O and F have the same number of neutrons.	
II.	C and N are isotopes of each other because their mass numbers are the same.	
III.	O2– has the same number of electrons as Ne.	

A)	I only	
B)	II only	
C)	III only	
D)	I and II only	
E)	I and III only	

ANS:	C	PTS:	1	DIF:	moderate	TOP:	 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	10.	Which among the following represent a set of isotopes? Atomic nuclei containing
I.	20 protons and 20 neutrons.	
II.	21 protons and 19 neutrons.	
III.	22 neutrons and 18 protons.	
IV.	20 protons and 22 neutrons.	
V.		21 protons and 20 neutrons.	

A)	I, V	
B)	III, IV	
C)	I, II, III	
D)	I, IV and II, V	
E)	No isotopes are indicated.	

ANS:	D	PTS:	1	DIF:	moderate	TOP:	 2.5
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	11.	How many protons, neutrons, and electrons does the atom 31P have?
A)	16 protons, 15 neutrons, 16 electrons	
B)	15 protons, 15 neutrons, 31 electrons	
C)	16 protons, 16 neutrons, 15 electrons	
D)	15 protons, 15 neutrons, 15 electrons	
E)	15 protons, 16 neutrons, 15 electrons	

ANS:	E	PTS:	1	DIF:	easy	TOP:	 2.6
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	12.	An ion is formed
 I.	by either adding protons to or subtracting protons from the atom.	
II.	by either adding electrons to or subtracting electrons from the atom.	
III.	by either adding neutrons to or subtracting neutrons from the atom.	

A)	Only I is true.	
B)	Only II is true.	
C)	Only III is true.	
D)	All of the statements are true.	
E)	Two of the statements are true.	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.6
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	13.	Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?
A)		
B)		
C)		
D)		

ANS:	D	PTS:	1	DIF:	easy	TOP:	 2.6
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	14.	Which of the following represents a pair of isotopes?
A)	157N, 158O	
B)	126C, 136C	
C)	188O, 199F	
D)	3216S, 3216S2–	
E)	O2, O3	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.6 | 2.7
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	15.	Which of the following statements is(are) true?
 I.	The number of protons is the same for all neutral atoms of an element.	
II.	The number of electrons is the same for all neutral atoms of an element.	
III.	The number of neutrons is the same for all neutral atoms of an element.	

A)	I, II, and III are all true.	
B)	I, II, and III are all false.	
C)	Only I and II are true.	
D)	Only I and III are true.	
E)	Only II and III are true.	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.6 | 2.7
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	16.	The ion 31P3– has
A)	15 protons, 15 neutrons, 12 electrons	
B)	15 protons, 15 neutrons, 3 electrons	
C)	15 protons, 31 neutrons, 15 electrons	
D)	15 protons, 16 neutrons, 18 electrons	
E)	15 protons, 15 neutrons, 15 electrons	

ANS:	D	PTS:	1	DIF:	easy	TOP:	 2.6 | 2.9
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	17.	The ion 127I– has
A)	53 protons, 74 neutrons, 52 electrons	
B)	53 protons, 74 neutrons, 54 electrons	
C)	53 protons, 53 neutrons, 53 electrons	
D)	53 protons, 74 neutrons, 53 electrons	
E)	53 protons, 127 neutrons, 54 electrons	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.6 | 2.9
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	18.	An element's most stable ion forms an ionic compound with chlorine having the formula XCl2. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?
A)	Mg, 12 neutrons	
B)	Ne, 16 neutrons	
C)	O, 16 neutrons	
D)	Ne, 14 neutrons	
E)	Na, 11 neutrons	

ANS:	A	PTS:	1	DIF:	moderate	TOP:	 2.6 | 2.9
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	19.	Which element does not belong to the family or classification indicated?
A)	I, halogen	
B)	K, alkali metal	
C)	Sn, lanthanides	
D)	Ar, noble gas	
E)	Fe, transition metal	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.7 | 2.8
KEY:	general chemistry | early atomic theory | periodic table

	20.	Which are alkaline earth halides?
A)	MgO, MgS, CaO	
B)	NaI, KBr, LiF	
C)	CaF2, MgBr2, SrI2	
D)	Al2O3, In2O3, Ga2S3	
E)	PbI2, PbBr2, CdF2	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.8 | 2.9
KEY:	general chemistry | early atomic theory | periodic table

	21.	Select the group of symbols that would correctly complete the following statements, respectively.
___ is the heaviest noble gas.
___ is the transition metal that has 24 electrons as a 3+ ion.
___ is the halogen in the third period.
___ is the alkaline earth metal that has 18 electrons as a stable ion.
A)	Rn, Cr, Br, Ca	
B)	Ra, Sc, Br, K	
C)	Ra, Co, Cl, K	
D)	Rn, Co, Cl, Ca	

ANS:	D	PTS:	1	DIF:	moderate	TOP:	 2.8 | 2.9
KEY:	general chemistry | early atomic theory | periodic table

	22.	______ form ions with a 2+ charge when they react with nonmetals.
A)	Halogens	
B)	Noble gases	
C)	Alkaline earth metals	
D)	Alkali metals	
E)	None of these choices	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.8
KEY:	general chemistry | early atomic theory | periodic table | group	

	23.	Which of the following formulas is not correct?
A)	Ba(OH)2	
B)	LiO	
C)	NaBr	
D)	CsCl	
E)	MgSO3	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.8
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	24.	Which of the following is not the correct chemical formula for the compound named?
A)	Fe3SO4             iron(III) sulfate	
B)	BaBr2             barium bromide	
C)	Li2O             lithium oxide	
D)	HCl             hydrogen chloride	
E)	Mg3N2             magnesium nitride	

ANS:	A	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	25.	Which of the following is not the correct name for the formula given?
A)	HClO             hypochlorous acid	
B)	Cr2O3             chromium(III) oxide	
C)	NCl3             nitrogen trichloride	
D)	CoO             cobalt(II) oxide	
E)	CaSO4             calcium sulfite	

ANS:	E	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound

	26.	Which is not the correct chemical formula for the compound named?
A)	iron(II) oxide             FeO	
B)	potassium sulfate             K2SO4	
C)	ammonium sulfide             NH4S	
D)	zinc nitrate             Zn(NO3)2	
E)	magnesium carbonate             MgCO3	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	27.	What is the correct formula for barium phosphate?
A)	Ba2PO4	
B)	Ba3(PO4)2	
C)	Ba2(PO4)3	
D)	Ba3PO4	
E)	BaPO4	

ANS:	B	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	28.	Which of the following is not the correct chemical formula for the compound named?
A)	HF             hydrogen fluoride	
B)	MgO             magnesium oxide	
C)	Fe3PO4             iron(III) phosphate	
D)	Li2O             lithium oxide	
E)	BaCl2             barium chloride	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound

	29.	Which formula is not correct?
A)	LiF	
B)	Ba(NO2)2	
C)	ZnBr	
D)	NaC2H3O2	
E)	CaO	

ANS:	C	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | chemical formula | ionic substance

	30.	What is the correct formula for chromium(VI) oxide?
A)	CrO6	
B)	CrO2	
C)	Cr2O3	
D)	Cr6O	
E)	CrO3	

ANS:	E	PTS:	1	DIF:	moderate	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	31.	Which of the following is not the correct name for the formula given?
A)	PCl5              phosphorus pentachoride	
B)	Fe2O3              iron(III) oxide	
C)	HClO              hypochlorous acid	
D)	BaSO3             barium sulfate	
E)	CoO             cobalt(II) oxide	

ANS:	D	PTS:	1	DIF:	easy	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	32.	Which of the following is not the correct chemical formula for the compound named?
A)	Al(OH)2             aluminum hydroxide	
B)	Mg(C2H3O2)2             magnesium acetate	
C)	ZnS             zinc sulfide	
D)	Fe2O3             iron(III) oxide	
E)	LiCN             lithium cyanide	

ANS:	A	PTS:	1	DIF:	moderate	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	33.	Which is the correct formula for gold(I) sulfide?
A)	AuS	
B)	AuS2	
C)	Au2S2	
D)	Au2S	
E)	Au2S3	

ANS:	D	PTS:	1	DIF:	moderate	TOP:	 2.9
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	34.	Complete the following table.

Symbol	Number of Protons	Number of Neutrons	Number of Electrons	Net Charge	
					
	31	38		3+	
	52	75	54		
		29		2+	

ANS:	

Symbol	Number of Protons	Number of Neutrons	Number of Electrons	Net Charge	
	82	124	82	0	
	31	38	28	3+	
	52	75	54	2–	
	25	29	23	2+	

PTS:	1	DIF:	difficult	TOP:	 2.6 | 2.7	
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

	35.	Complete the following table.

 Symbol	56Fe2+		
 Number of protons		35	
 Number of neutrons		45	
 Number of electrons			
 Atomic number			
 Mass number			
 Net charge		1-	

ANS:	
Symbol	56Fe2+	80Br-	
Number of protons	26	35	
Number of neutrons	30	45	
Number of electrons	24	36	
Atomic number	26	35	
Mass number	56	80	
Net charge	2+	1-	

PTS:	1	DIF:	difficult	TOP:	 2.6 | 2.7	
KEY:	general chemistry | early atomic theory | atomic theory of matter | isotope

Name the following compounds:

	36.	Al2(SO4)3

ANS:	
aluminum sulfate

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	37.	NH4NO3

ANS:	
ammonium nitrate

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	38.	NaH

ANS:	
sodium hydride

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	39.	K2Cr2O7

ANS:	
potassium dichromate

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	40.	CCl4

ANS:	
carbon tetrachloride

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | binary molecular compound	

	41.	AgCl

ANS:	
silver chloride

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	42.	CaSO4

ANS:	
calcium sulfate

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	43.	HNO3

ANS:	
nitric acid

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	44.	N2O3

ANS:	
dinitrogen trioxide

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | binary molecular compound	

	45.	SnI2

ANS:	
tin(II) iodide

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

Write the formula for:

	46.	sodium dichromate

ANS:	
Na2Cr2O7

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	47.	iron(III) oxide

ANS:	
Fe2O3

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	48.	dinitrogen trioxide

ANS:	
N2O3

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | binary molecular compound	

	49.	cobalt(II) chloride

ANS:	
CoCl2

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	50.	aluminum hydroxide

ANS:	
Al(OH)3

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	51.	hydrosulfuric acid

ANS:	
H2S

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	52.	sulfurous acid

ANS:	
H2SO3

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	53.	nitric acid

ANS:	
HNO3

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	54.	phosphoric acid

ANS:	
H3PO4

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	55.	acetic acid

ANS:	
HC2H3O2

PTS:	1	DIF:	easy	TOP:	 2.8	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | acid	

	56.	Write the chemical formulas for the following compounds or ions.

a) nitrate ion
	_________________
	
b) aluminum oxide
	_________________
	
c) ammonium ion
	_________________
	
d) perchloric acid
	_________________
	
e) copper(II) bromide
	_________________

ANS:	
a) NO3–   
b) Al2O3    
c) NH4+    
d) HClO4    
e) CuBr2

PTS:	1	DIF:	moderate	TOP:	 2.9	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound

	57.	Write the names of the following compounds:

a) FeSO4
	__________________________________________	
b) NaC2H3O2
	__________________________________________	
c) KNO2
	__________________________________________	
d) Ca(OH)2
	__________________________________________	
e) NiCO3	__________________________________________	

ANS:	
a) iron(II) sulfate    
b) sodium acetate   
c) potassium nitrite    
d) calcium hydroxide    
e) nickel(II) carbonate

PTS:	1	DIF:	moderate	TOP:	 2.9	
KEY:	general chemistry | early atomic theory | chemical substance | nomenclature of simple compound | ionic compound

	58.	Which nuclide has more protons than neutrons?
A)	Fe	
B)	K	
C)	Co	
D)	Ni	

ANS:	A	PTS:	1

	59.	An isotope of an element is formed

I.	by adding protons to, or removing protons from, the atom.	
II.	by adding neutrons to, or removing neutrons from, the atom.	
III.	by adding electrons to, or removing electrons from, the atom.	

A)	Only I is true	
B)	Only II is true	
C)	Only III is true	
D)	All of the statements are true	
E)	Two of the statements are true	

ANS:	B	PTS:	1

	60.	Which statement or statements regarding Antoine Lavoisier and his discovery of the conservation of mass in chemical reactions must be false.
A)	Lavoisier conducted his experiment in an apparatus that trapped all reaction products.	
B)	Lavoisier was able to make accurate mass measurements.	
C)	Lavoisier was able to make precise mass measurements.	
D)	Lavoisier did not trap gases in his experiments because their mass was negligible.	
E)	A and D	

ANS:	D	PTS:	1

	61.	The experiments of what two scientists were instrumental in determining the mass and charge of the electron?
A)	Lavoisier and Dalton	
B)	Rutherford and Curie	
C)	Thompson and Rutherford	
D)	Millikan and Cannizzaro	
E)	Thompson and Millikan	

ANS:	E	PTS:	1