Download Review Questions for 1st year chemistry

Review Questions for 1st year
chemistry
If gold has a density of 20 g/cm3, what is the
mass of a cube of gold with sides of 2 cm?
A. 160 g
B. 40 g
C. 20 g
D. 10 g
Answer: A Use density = mass/volume
20 = mass/(2×2×2)
20 = mass/8
so mass = 160
100. grams of water is heated from 30
degrees Celsius to 60 degrees Celsius,
calculate the amount of energy added.
A.10,000 J
B.12,500 J
C.16,300 J
D.40 kJ
Answer: B
100 g x 4.18 x 30 = 12540 J
Balance the following equation:
__Al + __H3PO4  __AlPO4 + __H2
A. 2,2,2,3
B. 1,2,2,4
C. 2,1,4,1
D. 3,1,3,3
Answer: A
Balance H’s so both sides are 6
Balance PO4’s as a group
Then balance Al’s last
How many electrons are in the VALENCE shell
of oxygen?
A. 16
B. 10
C. 8
D. 6
Answer: D
Oxygen has 8 electrons total but
two of them are in the first shell of the
Bohr Model. The six remaining electrons
are found in the outer shell of the model.
Which of the following statements is true
about the nucleus?
A. It is positively charged.
B. It contains only neutrons.
C. It is negatively charged.
D. It contains electrons and neutrons.
Answer: A
The nucleus has a positive charge because
it contains positively charged protons to
attract the electrons surrounding it.
What group on the periodic table contains
elements that are very malleable, are good
conductors, and are ductile?
A. Halogens
B. Alkaline-Earth Metals
C. Noble Gases
D. Metalloids
Answer: B
The structure of metals includes a sea of
electrons which allows heat to more easily
flow through the substance. It also allows
metals to bend without breaking easily.
Which of the following statements is true?
A. The reaction presented by the graph is endothermic.
B. The reaction presented by the graph is exothermic.
C. The reaction above has a negative delta H.
D. The reaction above has a catalyst.
Answer: A
The reaction presented by the graph is endothermic
because it is absorbing energy instead of releasing it,
shown by the positive change in delta H (difference
between products and reactants).
How many moles of O2 are in 64 grams of
O2?
A. 2.5
B. 4
C. 128
D. 2
Answer: D
64 g O2
1 mol O2 = 2 mol O2
32 g O2
What is the formula mass of 𝐾2 𝑆𝑖𝑂?
A. 83.19 g/mol
B. 122.29 g/mol
C. 120 g/mol
D. 244.58 g/mol
Answer: B
(39.098*2)+(28.085)+(16) = 122.29
If the wavelength of light is 5.8x10-7 m, what
color is the light?
A. Yellow
B. Orange
C. Blue
D. Green
Answer: A
Check reference table page 8.
Yellow is correct because the wavelength
falls between 5.7x10-7 m and 5.9x10-7 m.
Which of the following changes would
increase the pressure of a gas in a closed
container?
A. Increased volume of container
B. Increased number of particles in the
container
C. Decreased temperature
D. Decreased number of particles in the
container
Answer: B
The more particles there are in a container,
the more collisions that occur which raises
the pressure.
Which element has the highest electronegativity?
A. Chlorine
B. Iodine
C. Fluorine
D. Bromine
Answer: C
Electronegativity decreases as you move
down the periodic table because as you move
down, there are more valence shells which
shield the pull of the protons in the nucleus.
Fluorine is the first element in its group and
therefore has the highest electronegativity.
For an atom that is neutral, which of the
following statements is FALSE?
A. The number of protons is equal to the
number of neutrons.
B. The atomic number is equal to the
number of protons.
C. The number of protons is equal to the
number of electrons.
D. The atomic mass is equal to the sum of
protons and neutrons in the atom.
Answer: A
Which of the following has the highest
boiling point?
A. CH4
B. CO2
C. SO2
D. HF
Answer: D
An H-F bond is a type of hydrogen bond.
This bond has a stronger intermolecular
force, so it will have the higher boiling
point.
The molecular geometric shape of H2S is:
A. Bent
B. Linear
C. Trigonal Planar
D. Trigonal Pyramidal
Answer: A
Since the lone pairs want to repel each other,
it causes the bond pairs to bend towards
each other, causing the molecular form of the
compound to be bent.
If an electron drops from the 6th energy
level to the 2nd, what type of light is
released?
A. Visible
B. Infra-red
C. Ultraviolet
D. X rays
Answer: A
Visible is correct because the wavelength
of light released based on the Bohr model
falls in the visible light range. Use page 8
of the reference tables.
Which image shows a representation of a
compound?
A. A
B. B
C. C
D. None of the images
Answer: B
The molecules are made of two kinds of
atoms bonded together. All particles are
the same.
19 grams of water are heated from ice at 0
degrees Celsius to 15 degrees Celsius,
calculate the amount of energy added.
A. 9,000 J
B. 7,500 J
C. 17 kJ
D. 1,900 J
Answer: B
(19 x 4.18 x 15) + (19 x 334) = 7537.3
What is the percent composition of
hydrogen in ethylene glycol (𝐶2 𝐻6 𝑂2 )?
A. 1.62%
B. 10.00%
C. 4.87%
D. 9.74%
Answer: D
(1.008 × 6)/62.068 × 100 = 9.74%
What type of bonding is found between
carbon and hydrogen in CH4?
A. Metallic
B. Covalent
C. Ionic
Answer: B
A bond between two nonmetals is covalent.
Both Carbon and Hydrogen are nonmetals so
the bond between them is Covalent.
The volume of a gas at 99.0 kPa is 300 mL. If
the pressure increases to 188 kPa, what is
the final volume?
A. 569 mL
B. 52.1 mL
C. 158 mL
D. None of the above
Answer: C
Using Boyle’s Law P1V1=P2V2, to find the
final volume. 99.0 × 300 = 188 × V2
What does T represent on the graph?
A. The products of the reaction.
B. The reverse activation energy.
C. The effects of a catalyst.
D. The heat of reaction.
Answer: D
T displays the energy absorbed during the reaction,
which is the positive difference between Y
(reactants) and X (products) in this case.
How many moles are in 25 grams of water?
A. 1.6 moles
B. 1.39 moles
C. 1.48 moles
D. 11.39 moles
Answer: B
25 g H2O 1 mol H2O = 1.39 mol H2O
18.02 g H2O
What type of reaction is this?
PbCl2 + AgNO3 —-> Pb(NO3)2 + AgCl
A. combustion
B. decomposition
C. synthesis
D. double replacement
Answer: D
Because two compounds traded ions.
Which element matches the following Bohr model?
A. Boron
B. Magnesium
C. Neon
D. Sodium
Answer: D
Sodium has 11 electrons and needs 3
electron shells. The Bohr model
represents the electrons by the 11 dots.
As you move across the periodic table
A. Atomic radii increases
B. Atomic radii decreases
C. Atomic radii stay the same size
Answer: B
As you move across the periodic table,
elements have more protons. Their
increasingly stronger pull on the outer shell
draws the outer shell closer to the nucleus,
decreasing the size of the element.
Which of the following elements will NOT be
surrounded by an octet of electrons in a
correctly drawn Lewis structure?
A. Hydrogen
B. Oxygen
C. Chlorine
D. Carbon
Answer: A
The hydrogen atom only has one valence
electron in the outermost shell. Its outer
shell (its only shell) is the 1s orbital,
which only needs two electrons.
1s22s22p63s2 is what element?
A. magnesium
B. manganese
C. sodium
D. silicon
Answer: A
Magnesium has 12 electrons. It is located
in the 3rd row, 2nd column.
An ice cube is placed in a cup of hot tea.
What is the nature of the change that
occurs?
A. The ice becomes liquid water,
chemical change
B. The ice becomes tea, chemical change
C. The ice becomes liquid water, physical
change
D. The ice becomes tea, physical change
Answer: C
Ice melting is a physical change from
solid to liquid.
What is it called when a solid proceeds
directly to the gas state skipping the liquid
state?
A. Sublimation
B. Deposition
C. Vaporization
D. Freezing
Answer: A
What is the empirical formula of
propanedinitrile (C8H4N2 ) ?
A. C8H4N2
B. C16H8N4
C. C4H2N
D. CHN
Answer: C
Simplify the subscripts. Empirical
formula has the most simplified ratio.
At what temperature will 0.654 moles of
neon gas occupy 12.30 L at 1.95 atm?
A. 447 K
B. 18 K
C. 273 K
D. None of the above
Answer: A
Using the ideal gas law, PV=nRT, T=PV/nR,
plug in all the given information and solve
for the temperature.
1.95 × 12.30 = 0.654 × 0.0821 × T
Different isotopes of an element have
different numbers of _____________?
A. neutrons
B. protons
C. voltrons
D. electrons
Answer: A
Different numbers of neutrons result in
different masses.
What is the molar mass of Ca3 N2 ?
A. 150.00 g/mol
B. 148.25 g/mol
C. 54.09 g/mol
D. 100.0 g/mol
Answer: B
(40.078 × 3) + (14.01 × 2) = 148.25
Which of the following does not form
hydrogen bonds?
A. H2S
B. H2O
C. NH3
D. HF
Answer: A
Hydrogen bonds can occur when a
hydrogen atom is attracted to either a
nitrogen atom, a fluorine atom, or an
oxygen atom.
What does U represent on the graph?
A. The activation energy for the forward reaction.
B. The activation energy for the reverse reaction.
C. The heat of reaction.
D. The effect of a catalyst.
Answer: B
U represents the energy required to undergo the
reverse reaction from X back to Y.
If an atom’s outermost electron is in a
d-orbital then the atom is a(n)
A. alkali metal.
B. alkaline-earth metal.
C. halogen.
D. transition metal.
Answer: D
Transition metal because only transition
metals have an outermost electron in
the d-orbital.
What happens to water as it boils?
A. The hydrogen and oxygen atoms
separate and become gases.
B. The water molecules move slower.
C. Nothing
D. Hydrogen bonds between molecules
break.
Answer: D
Water’s molecules remain intact, but
bonds between molecules are
weakened.
What is the point at which a substance
coexists in solid, liquid, and gaseous forms?
A. equivalence point
B. equilibrium point
C. triple point
D. physical point
Answer: C
What kind of compound is Ca3N2?
A. Covalent
B. Ionic
C. Metallic
D. Other
Answer: B
It is composed of a metal and a nonmetal.
Which of the following is a part of Dalton’s
Atomic Theory?
A. All matter is made up of atoms.
B. Atoms cannot be subdivided, created,
or destroyed.
C. Atoms of different elements can
combine in whole-number ratios to
form chemical compounds.
D. All of the above
Answer: D
Dalton’s Atomic Theory states all of these.
The half-life of beryllium-14 is 4.84 seconds.
How much of a 16 gram sample of beryllium-14
is left after 14.52 seconds?
A. 4 g
B. 8 g
C. 20 g
D. 2 g
Answer: D
14.52/4.84 = 3 half-lives
16/2/2/2 = 2 g (cut 16 in half 3 times)
Identify the correct products:
Na + CaF2 
A. NaF + Ca
B. Ca2F + Na
C. No reaction
D. NaF2 + Ca
Answer: C
Na is below Ca on the activity series.
Always check the activity series for
single replacement reactions.
What is FALSE about the relationship
between 147N and 167N?
A. These are two different isotopes of
nitrogen.
B. Both atoms have 7 protons.
C. The atoms have different atomic masses.
D. Both atoms have 7 neutrons.
Answer: D
These isotopes have different masses (14
and 16), but the same number of protons
(7). To find the neutrons, calculate mass
minus protons.
Which of the following is the best example
of a trigonal planar molecule?
A. CO2
B. BF3
C. NH3
D. H2O
Answer: B
This molecule does not have enough
valence electrons to follow the octet rule
because it only needs six valence electrons.
The fluorine atoms repel each other at 120
degree angles.
The wavelength of light released when an
electron drops from n=4 to n=3 is
A. 1282 nm
B. 656 nm
C. 1875 nm
D. 97 nm
Answer: C
According to the Bohr model on page 8 of
the reference tables, the wavelength is
1875 nm when the electron makes that
transition from ring 4 to ring 3.
A+B↔C
What is the equilibrium constant for
this reaction?
A.
B. [A][B]
C.
D.
Answer: D
Keq = products divided by reactants
In what state is water at extremely low
pressure and high temperature according to
a phase diagram?
A. Liquid
B. Gas
C. Solid
D. Solid and Liquid
Answer: B
What is the formula of lithium phosphate?
A. Li2PO4
B. Li3 PO3
C. Li2PO2
D. Li3PO4
Answer: D
Lithium has a +1 charge, and phosphate
has a -3 charge. You can look up
phosphate on the list of polyatomic
ions. When you cross charges, your
subscripts will be 3 and 1, respectively.
What is the forward activation energy for the
following reaction? (in kilojoules)
A. 20 kJ
B. 50 kJ
C. 100 kJ
D. 150 kJ
Answer: B
The activation energy is represented by (a), and is
the difference between 200 kJ and 150 kJ.
The pressure of a mixture of nitrogen, carbon
dioxide, and oxygen is 150 kPa. What is the
partial pressure of oxygen if the partial
pressure of nitrogen is 100 kPa and that of
carbon dioxide is 24 kPa?
A. 51 kPa
B. 26 kPa
C. 35 kPa
D. Not enough information is given
Answer: B
Dalton’s Law of Partial Pressures:
Ptotal=P1+P2+P3+… Plug in the given pressures
and subtract to solve.
When a metal oxide reacts with water,
_______________ is always produced.
A. a base
B. a pink precipitate
C. an acid
D. some bubbles
Answer: A
This is a synthesis type 1b reaction.
MO + H2O  base
Remember that bases have the formula MOH.
Which ion is represented by this Bohr model?
A. Si2B. Neon
C. Al3+
D. Ca+2
Answer: C
The aluminum ion has a positive charge
of 3, thus losing 3 electrons. 13 – 3 = 10
So its Bohr model would have 10 electrons.
Which of these types of electromagnetic
radiation has the highest frequency?
A. X rays
B. Visible Light
C. Microwaves
D. Radio waves
Answer: A
It has the shortest wavelength and
therefore the highest frequency. Use page
8 of the reference tables.
What type of reaction is:
C2H4 + O2  CO2+ H2O
A. combustion
B. decomposition
C. synthesis
D. double replacement
Answer: A
It is a reaction between a hydrocarbon and
oxygen that produces CO2 and H2O.
Reaction type 5 in the reference tables.
Which set contains a correctly named
chemical formula?
A. Iron(III) phosphate, FePO4
B. Iron(II) phosphate, FePO4
C. Iron phosphate, FePO4
D. None of the above
Answer: A
Iron has to show its charge in its name
because it may vary in charge number.
Because the iron and phosphate have the
same charge, they have a 1:1 mole ratio.
A gas at 89C occupies a volume of 0.671 L.
At what temperature will the volume
increase to 1.12 L?
A.66.7C
B.331C
C.100C
D.None of the above
Answer: B
Put T1 in Kelvin, use Charles’ Law :
V1/T1=V2/T2, to find the final temperature,
then convert back to Celsius
Predict the products of the reaction
NaHCO3
A. Na + H2 + CO2
B. Na2O + H2O + CO2
C. NaO + H2O + CO2
D. C2H6 + Na
Answer: B
This is a decomposition type 2c, metallic hydrogen
carbonate decomposes into metal oxide, water and
carbon dioxide.
MHCO3 MO + H2O + CO2
Remember to cross charges to get formula for MO.
How many electrons are in the sodium ion?
(Na+ )
A. 23
B. 20
C. 11
D. 10
Answer: D
When an ion of sodium forms, it loses an
electron. Originally sodium has 11 electrons
so when the ion forms, the number of
electrons decreases to 10 to have a filled
outer shell.
Which of the following changes to a system
will not result in an increase in pressure?
A. Adding more gas molecules
B. Increasing the volume of the container
C. Raising the temperature
D. Decreasing the volume of the container
Answer: B
Increasing the volume of the container
gives the molecules more room, thus
decreasing the number of collisions with
the surfaces and decreasing the pressure.