CEM 141 PRACTICE EXAM QUESTIONS AND
ANSWERS
Which has a larger atomic radius? Mg or Ar? Why?
A. Mg, because it is a metal.
B. Mg, because its valence electrons are not as strongly attracted towards
the nucleus as those in Ar.
C. Ar, because it is a heavier element.
D. Ar, because it has more electrons and they repel each other. - -B
- Out of Na+, Mg2+, Ne, and F- which has the smallest radius?
A. Na+
B. Mg2+
C. Ne
D. F- - -B
- When and where were the carbon and oxygen atoms in your body created?
A. In plants as they were growing
B. During the big bang
C. Within stars and stellar explosions
D. During the course of digesting your food - -C
- Iodine and silicone dioxide are both solid at room temperature. Which has
a higher melting point and why?
A. I2 because it is heavier and therefore has the largest LDFs
B. I2 because it is an element
C. Silicon dioxide because to melt it you would have to break covalent bonds
D. Silicon dioxide, because it is a compound - -C
- Does one molecule of water have a boiling point?
A. yes
B. no - -B
- Why do covalent bonds form?
I. Because atoms want to share electrons.
II. Because electrons from one atom are attracted to the nucleus of another
atom.
III. Because atoms want an octet of electrons around them.
IV. Because the formation of a bond results in a stable system that would
require the input of energy to change.
A. I
B. II and IV
C. III
D. I and II - -B
, - Which of the following are correct statements?
I. Covalent bonds are interactions WITHIN MOLECULES.
II. Covalent bonds are interactions BETWEEN SEPARATE MOLECULES.
III. LDF's are typically interactions BETWEEN SEPARATE MOLECULES, but can
occur within a single large molecule.
IV. LDF's are WITHIN MOLECULES.
A. I
B. II
C. I and III
D. I and IV - -C
- Why are metals shiny?
A. Because they reflect most of the light falling on them.
B. Because they refract most of the light falling on them.
C. Because they absorb photons and re-emit them.
D. Because photons are generated as electrons move up to higher molecular
orbitals. - -C
- If a reaction occurs between a compound that has a lemon smell and one
that has a rose smell, what will the product smell like?
A. Lemon
B. Roses
C. Lemon and roses
D. It is impossible to predict the smell of the product - -D
- Why is nuclear fusion not a viable option for generating energy at the
moment?
A. It is far too dangerous
B. The high energy requirement to overcome the Coulombic repulsion of the
nuclei
C. The radioactive isotopes produced cannot be contained
D. It is impossible to find a vessel that will contain the plasma needed for
fusion - -B
- Element X exists as diatomic molecules held together by 3 covalent bonds,
while element Y exists as a 3D network of single covalent bonds. Element X
has a higher atomic mass than element Y. Which element is most likely to
have the highest melting point?
A. X, because it has a triple bond that must be broken in order for it to melt.
B. X, because it has a higher molecular weight.
C. Y, because all the bonds in the 3D network must break for the substance
to melt.
D. Y, because sigma bonds are stronger than pi bonds. - -C
- If you start with 16g of methane and 16g of oxygen, how much carbon
dioxide would you produce?
ANSWERS
Which has a larger atomic radius? Mg or Ar? Why?
A. Mg, because it is a metal.
B. Mg, because its valence electrons are not as strongly attracted towards
the nucleus as those in Ar.
C. Ar, because it is a heavier element.
D. Ar, because it has more electrons and they repel each other. - -B
- Out of Na+, Mg2+, Ne, and F- which has the smallest radius?
A. Na+
B. Mg2+
C. Ne
D. F- - -B
- When and where were the carbon and oxygen atoms in your body created?
A. In plants as they were growing
B. During the big bang
C. Within stars and stellar explosions
D. During the course of digesting your food - -C
- Iodine and silicone dioxide are both solid at room temperature. Which has
a higher melting point and why?
A. I2 because it is heavier and therefore has the largest LDFs
B. I2 because it is an element
C. Silicon dioxide because to melt it you would have to break covalent bonds
D. Silicon dioxide, because it is a compound - -C
- Does one molecule of water have a boiling point?
A. yes
B. no - -B
- Why do covalent bonds form?
I. Because atoms want to share electrons.
II. Because electrons from one atom are attracted to the nucleus of another
atom.
III. Because atoms want an octet of electrons around them.
IV. Because the formation of a bond results in a stable system that would
require the input of energy to change.
A. I
B. II and IV
C. III
D. I and II - -B
, - Which of the following are correct statements?
I. Covalent bonds are interactions WITHIN MOLECULES.
II. Covalent bonds are interactions BETWEEN SEPARATE MOLECULES.
III. LDF's are typically interactions BETWEEN SEPARATE MOLECULES, but can
occur within a single large molecule.
IV. LDF's are WITHIN MOLECULES.
A. I
B. II
C. I and III
D. I and IV - -C
- Why are metals shiny?
A. Because they reflect most of the light falling on them.
B. Because they refract most of the light falling on them.
C. Because they absorb photons and re-emit them.
D. Because photons are generated as electrons move up to higher molecular
orbitals. - -C
- If a reaction occurs between a compound that has a lemon smell and one
that has a rose smell, what will the product smell like?
A. Lemon
B. Roses
C. Lemon and roses
D. It is impossible to predict the smell of the product - -D
- Why is nuclear fusion not a viable option for generating energy at the
moment?
A. It is far too dangerous
B. The high energy requirement to overcome the Coulombic repulsion of the
nuclei
C. The radioactive isotopes produced cannot be contained
D. It is impossible to find a vessel that will contain the plasma needed for
fusion - -B
- Element X exists as diatomic molecules held together by 3 covalent bonds,
while element Y exists as a 3D network of single covalent bonds. Element X
has a higher atomic mass than element Y. Which element is most likely to
have the highest melting point?
A. X, because it has a triple bond that must be broken in order for it to melt.
B. X, because it has a higher molecular weight.
C. Y, because all the bonds in the 3D network must break for the substance
to melt.
D. Y, because sigma bonds are stronger than pi bonds. - -C
- If you start with 16g of methane and 16g of oxygen, how much carbon
dioxide would you produce?
