Chem 121 Final exam practice
Which of the following statements is TRUE?
a) Carbon is a diatomic molecule
.b) Elements in the same group on the periodic table have similar chemical properties.
c) Intensive physical properties depend on the amount of the substance present.
d) The SI unit for temperature is Celsius.
e) One cL of water is less than one mL of water. - answer Elements in the same group
on the periodic table have similar chemical properties.
C is not one of 7 diatomics, intensive properties are independent of amount, SI unit of
temperature is Kelvin, and one centiliter (cL) is more than one milliliter (mL).
How many protons (p), electrons (e) and neutrons (n) are in an atom of calcium-46
(46Ca)?
a) 20 p, 20 e, 26 n
b) 20 p, 20 e, 46 n
c) 26 p, 20 e, 20 n
d) 46 p, 46 e, 60 n
e) 20 p, 26 e, 26 n - answera) 20 p, 20 e, 26 n
Calcium has an atomic number of 20 so 20 protons. Since an atom has the same
number of electrons. Isotope has mass number of 46 (p + n) so must have 26 neutrons.
An element has two naturally occurring isotopes. One has an abundance of 37.40% and
an isotopic mass of 184.953 amu, and the other has an abundance of 62.60% and a
mass of 186.956 amu. What is the atomic weight of the element (to 4 sig figs)?
a) 185.7 amu
b) 185.0 amu
c) 186.2 amu
d) 187.0 amu
e) 189.4 amu - answeratomic wt = (0.3740)(184.953amu) + (0.6260)(186.956) = 186.2
amu
What is the molar mass (molecular weight) of Co(NO3)2?
a) 91.94 g/mol
b) 120.9 g/mol
c) 167.0 g/mol
d) 183.0 g/mol
e) 152.9 g/mol - answerCo = 58.93 g/mol
2 N = 2(14.01) = 28.02 g/mol
6 O = 6(16.00) = 96.00 g/mol
Co(NO3)2 = 182.95 = 183.0 g/mol
, The following are all properties of chlorine. Which of the following does NOT describe a
physical property of chlorine?
a) Chlorine combines with sodium to form table salt.
b) The color of chorine gas is green.
c) The density of chlorine gas at standard temperature and pressure is 3.17 g/L.
d) The freezing point of chlorine is -101 °C.
e) All of the above describe the physical properties of chlorine. - answera) Chlorine
combines with sodium to form table salt is a chemical property.
The mass of a proton is 1.67 × 10-27 kg. What is the mass of a proton in Gigagrams?
a) 1.67 × 1039 Gg
b) 1.67 × 10-36 Gg
c) 1.67 × 10-33 Gg
d) 1.67 × 10-30 Gg
e) 1.67 x 1030 Gg - answer1.67x10-27 kg x 1000 g/1kg x 1 Gg/1x10^9 g = 1.67 x 10-33
Gg
Which of the following is a pure element?
a) salt water
b) carbon monoxide
c) tin
d) milk
e) None of these are pure elements. - answerc) tin
a) TRUE or (b) FALSE. The mass percent of carbon in CO2 is higher than the mass
percent ofcarbon in H2CO - answerFalse; mass% C in CO2 = 12.01/44.01 x100 =
27%mass% C in H2CO = 12.01/30.03 x100 = 40%
Which statement is FALSE?
a) Fluorine is a poor conductor of heat and electricity.
b) Neon is a gas at room temperature.
c) Most elements are solids at room temperature.
d) Germanium is a metalloid (semimetal)
.e) Group 2 elements are called alkali metals. - answerE) group 2 elements are called
alkaline earth metals.
Compound A is a gas at room temperature (and one-atmosphere pressure) while
compound B is a solid at room temperature with a melting point of 1,368 C. Based
solely on these data, one would expect:
a) both compounds to be covalent.
b) compound A to be ionic and compound B to be covalent.
c) compound A to be covalent and compound B to be ionic.
d) both compounds to be ionic.
e) both compounds to be metallic. - answerb) compound A to be ionic and compound B
to be covalent.
Which of the following statements is TRUE?
a) Carbon is a diatomic molecule
.b) Elements in the same group on the periodic table have similar chemical properties.
c) Intensive physical properties depend on the amount of the substance present.
d) The SI unit for temperature is Celsius.
e) One cL of water is less than one mL of water. - answer Elements in the same group
on the periodic table have similar chemical properties.
C is not one of 7 diatomics, intensive properties are independent of amount, SI unit of
temperature is Kelvin, and one centiliter (cL) is more than one milliliter (mL).
How many protons (p), electrons (e) and neutrons (n) are in an atom of calcium-46
(46Ca)?
a) 20 p, 20 e, 26 n
b) 20 p, 20 e, 46 n
c) 26 p, 20 e, 20 n
d) 46 p, 46 e, 60 n
e) 20 p, 26 e, 26 n - answera) 20 p, 20 e, 26 n
Calcium has an atomic number of 20 so 20 protons. Since an atom has the same
number of electrons. Isotope has mass number of 46 (p + n) so must have 26 neutrons.
An element has two naturally occurring isotopes. One has an abundance of 37.40% and
an isotopic mass of 184.953 amu, and the other has an abundance of 62.60% and a
mass of 186.956 amu. What is the atomic weight of the element (to 4 sig figs)?
a) 185.7 amu
b) 185.0 amu
c) 186.2 amu
d) 187.0 amu
e) 189.4 amu - answeratomic wt = (0.3740)(184.953amu) + (0.6260)(186.956) = 186.2
amu
What is the molar mass (molecular weight) of Co(NO3)2?
a) 91.94 g/mol
b) 120.9 g/mol
c) 167.0 g/mol
d) 183.0 g/mol
e) 152.9 g/mol - answerCo = 58.93 g/mol
2 N = 2(14.01) = 28.02 g/mol
6 O = 6(16.00) = 96.00 g/mol
Co(NO3)2 = 182.95 = 183.0 g/mol
, The following are all properties of chlorine. Which of the following does NOT describe a
physical property of chlorine?
a) Chlorine combines with sodium to form table salt.
b) The color of chorine gas is green.
c) The density of chlorine gas at standard temperature and pressure is 3.17 g/L.
d) The freezing point of chlorine is -101 °C.
e) All of the above describe the physical properties of chlorine. - answera) Chlorine
combines with sodium to form table salt is a chemical property.
The mass of a proton is 1.67 × 10-27 kg. What is the mass of a proton in Gigagrams?
a) 1.67 × 1039 Gg
b) 1.67 × 10-36 Gg
c) 1.67 × 10-33 Gg
d) 1.67 × 10-30 Gg
e) 1.67 x 1030 Gg - answer1.67x10-27 kg x 1000 g/1kg x 1 Gg/1x10^9 g = 1.67 x 10-33
Gg
Which of the following is a pure element?
a) salt water
b) carbon monoxide
c) tin
d) milk
e) None of these are pure elements. - answerc) tin
a) TRUE or (b) FALSE. The mass percent of carbon in CO2 is higher than the mass
percent ofcarbon in H2CO - answerFalse; mass% C in CO2 = 12.01/44.01 x100 =
27%mass% C in H2CO = 12.01/30.03 x100 = 40%
Which statement is FALSE?
a) Fluorine is a poor conductor of heat and electricity.
b) Neon is a gas at room temperature.
c) Most elements are solids at room temperature.
d) Germanium is a metalloid (semimetal)
.e) Group 2 elements are called alkali metals. - answerE) group 2 elements are called
alkaline earth metals.
Compound A is a gas at room temperature (and one-atmosphere pressure) while
compound B is a solid at room temperature with a melting point of 1,368 C. Based
solely on these data, one would expect:
a) both compounds to be covalent.
b) compound A to be ionic and compound B to be covalent.
c) compound A to be covalent and compound B to be ionic.
d) both compounds to be ionic.
e) both compounds to be metallic. - answerb) compound A to be ionic and compound B
to be covalent.
