Answers26-27 CFISD TX-Chemistry A CRLab: Physical and Chemical Changes

Lab: Physical and Chemical Changes — Unit test Answers

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When a strip of magnesium metal is touched to a flame, a bright light and a whitish substance are produced. Why is the burning of magnesium considered a chemical change?

A
because the metal reaches a high temperature
B
because the metal begins to melt
C
because a new substance is formed
D
because the metal is malleable
2
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Which sequence represents the relationship between pressure and volume of an ideal gas as explained by the kinetic-molecular theory?

A
more gas particles more collisions higher pressure
Option A
B
smaller volume crowded particles less collisions lower pressure
Option B
C
smaller volume crowded particles more collisions higher pressure
Option C
D
more gas particles more kinetic energy more volume higher pressure
Option D
3

The diagram below shows the different phase transitions that occur in matter.Which best describes the process that arrow 1 represents?

Question illustration
A
Molecules are speeding up during boiling.
B
Molecules are depositing as ice on a surface.
C
Molecules are slowing down during condensing.
D
Molecules are moving from stationary positions.
4

Which is a postulate of the kinetic-molecular theory?

A
Gas particles have a small volume relative to the spaces between them.
B
Gas particles have a large volume relative to the spaces between them.
C
Gas particles are very small in size and always move slowly.
D
Gas particles are very large in size and always move slowly.
5

The diagrams show gases that are stored in two separate but similar containers.If both gases are at the same temperature, which one has the greater pressure?

Question illustration
A
gas 1 because the particles are moving much faster
B
gas 1 because it has fewer particles that are close together
C
gas 2 because it has more particles that are colliding
D
gas 2 because the particles have more space between them
6

Which best characterizes a crystal?

A
a number of high speed particles moving randomly
B
a dense substance that is hard and incompressible
C
a high-energy state of matter made up of a swirling, ionized gas
D
a loose association of particles moving past one another
7

The diagrams show the particles of a substance.Which statement best describes the process that the diagrams show?

Question illustration
A
A solid loses kinetic energy to become a liquid and then becomes a gas.
B
A solid gains kinetic energy to become a liquid and then becomes a gas.
C
A gas loses kinetic energy to become a liquid and then becomes a solid.
D
A gas gains kinetic energy to become a liquid and then becomes a solid.
8

Which statement describes a chemical property of water?

A
It reacts with sodium metal.
B
It has a melting point of 0°C.
C
It has a density of about 1 g/mL.
D
It is clear and colorless.
9

Why do amorphous solids not have a long-range order in the arrangement of their particles?

A
Their formation involves very rapid cooling.
B
They do not have enough particles.
C
Their particles eventually change positions.
D
Their particles always stay in the same positions.
10

Which commercial technology commonly uses plasmas?

A
a radio
B
a race car
C
a fluorescent light
D
a microwave oven
11

Which of these is an example of a physical change?

A
sugar, when heated, producing carbon dioxide and water
B
solid ice, when heated, turning into liquid water
C
sodium, when exposed to chlorine, forming sodium chloride
D
aluminum, when heated in air, forming aluminum oxide
12

Which is an aspect of the kinetic-molecular theory and can be used to explain the compressibility of plasmas?

A
Particles move independently of one another and are widely spaced.
B
Particle kinetic energy increases with increasing temperature.
C
Particles exert no attractive or repulsive force on one another.
D
Particles always move even when they have fixed positions.
13

A gaseous substance turns directly into a solid. Which term describes this change?

A
deposition
B
evaporation
C
melting
D
sublimation
14

Which statement describes a limitation of the kinetic-molecular theory for a gas?

A
The theory assumes that particles do not experience intermolecular forces.
B
The theory states that pressure is inversely proportional to volume.
C
The theory assumes that particles are in random and continuous motion.
D
The theory states that pressure increases with temperature.
15

Which statement describes an extensive property of matter?

A
It changes with the color of a substance.
B
It changes when a new substance is formed.
C
It changes with the amount of sample that is present.
D
It changes with the composition of a substance.

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