| Questions |
Answers |
Explanations |
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11 Which grouping of the three phases of
bromine is listed
in order from left to right for increasing distance
between bromine
molecules?
(1) gas, liquid,
solid (3) solid, gas,
liquid
(2) liquid, solid,
gas (4) solid, liquid, gas |
4 |
Solid
is the most compact phase, then liquid and finally gas |
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12 Which statement concerning elements
is true?
(1) Different elements must have
different numbers of
isotopes.
(2) Different elements must have
different numbers of
neutrons.
(3) All atoms of a given element must
have the same
mass number.
(4) All atoms of a given element must
have the same
atomic number.
|
4 |
All
atoms of an element have the same atomic number
(protons) |
|
13 At room temperature, the solubility
of which solute
in water would be most affected by a change
in pressure?
(1)
methanol
(3) carbon dioxide
(2)
sugar
(4) sodium nitrate
|
3 |
Pressure
only effects gases |
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14 Based on Reference Table
I,
which change occurs
when pellets of solid NaOH are added to water
and stirred?
(1) The water temperature increases as
chemical energy
is converted to heat energy.
(2) The water temperature increases as
heat energy is
stored as chemical energy.
(3) The water temperature decreases as
chemical energy
is converted to heat energy.
(4) The water temperature decreases as
heat energy is
stored as chemical energy.
|
1 |
since
delta H is negative, the dissolving is exothermic and
the temperature of the water increase |
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15 The concept of an ideal gas is used
to explain
(1) the mass of a gas sample
(2) the behavior of a gas sample
(3) why some gases are monatomic
(4) why some gases are diatomic |
2 |
how
gases behave |
|
16 Molecules in a sample of NH 3(l)
are held closely together
by intermolecular forces
(1) existing between ions
(2) existing between electrons
(3) caused by different numbers of
neutrons
(4) caused by unequal charge
distribution
|
4 |
intermolecular
forces are between molecules and caused by the unequal
distribution of charge in the molecules |
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17 Which process represents a chemical
change?
(1) melting of ice
(2) corrosion of copper
(3) evaporation of water
(4) crystallization of sugar |
2 |
chemical
changes, look for the reaction
physical is phase changes |
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18 At STP, which 4.0-gram zinc sample
will react fastest
with dilute hydrochloric acid?
(1) lump (3) powdered
(2) bar
(4) sheet metal
|
3 |
surface
area, more surface more places to react |
|
19 Which information about a chemical
reaction is provided by a potential energy diagram?
(1) the oxidation states of the
reactants and products
(2) the average kinetic energy of the
reactants and
products
(3) the change in solubility of the
reacting substances
(4) the energy released or absorbed
during the reaction |
3 |
PE
diagrams provide a way to show energy changes in a
reaction |
|
20 A catalyst works by
(1) increasing the potential energy of
the reactants
(2) increasing the energy released
during a reaction
(3) decreasing the potential energy of
the products
(4) decreasing the activation energy
required for a
reaction
|
4 |
definition-
lowers activation energy |
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