Name:
Topic: Physical Quantities and Measurement Date:
Subtopic: Density/Floating and Sinking
Science | Grade 8
10 min | I took min
1. Select the correct Statement:
a. Gases can be compressed, but liquids cannot. Which statement explains this
difference?
i Each molecule in a gas is more compressible than each molecule in a
liquid.
ii Molecules in a gas are further apart than molecules in a liquid.
iii Molecules in a gas attract each other more strongly than molecules in a
liquid.
iv Molecules in a gas move more slowly than molecules in a liquid.
b. The diagram shows the changes of state P, Q, R
and S that occur in solids, liquids and gases.
What is the name of change R?
i Condensation ii Solidification
iii Boiling iv Melting
c. Which statement is correct?
i A solid can flow. ii A solid can be compressed easily
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iii iv A solid takes the shape of its
A solid has a fixed shape.
container.
d. When a liquid evaporates, some molecules escape. The temperature of the
remaining liquid changes. What is the effect on the temperature and from
where do the molecules escape?
Temperature of Liquid Molecules escape from
i. decreases Everywhere within the liquid
ii. decreases The surface only
iii. increases Everywhere within the liquid
iv. increases The surface only
2. Define the following.
a. Force of adhesion.
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b. Matter
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c. Force of cohesion
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d. Freezing
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e. Melting
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3. Answer the following questions:
a. Water can exist as ice, liquid water and steam.
Figure represents the arrangement of the
molecules in the three forms of water.
Each diagram below shows a change of state. Add the correct label for each
change. The first has been done for you.
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b. What are the characteristics of molecules?
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c. Explain the statement that molecules are in random motion with respect to
solids, liquids and gases.
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d. At the parade, some air-filled balloons are
used as decorations, as shown in figure.
i. State what happens to the balloons when the Sun makes them hotter.
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ii. In terms of molecules, explain your answer to (d)(i).
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e. Some gas molecules are in a box at
room temperature as shown.
Describe the movement of the gas
molecules
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4. In the figure below, small circles represent molecules. The arrows refer to the
change of state from the arrangement of molecules on the left to the
arrangement of molecules on the right.
a. Complete the following by writing solid, liquid or gas in each of the blank
spaces.
i. Change of state X is from ________________ to ___________________.
ii. Change of state Y is from ________________ to ___________________.
b. Explain, in terms of the forces between their molecules, why gases expand
more than solids when they undergo the same rise in temperature.
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5. A student draws diagrams that represent three states of matter, as shown in
below figure. Box B shows the arrangement of particles in a liquid
a. In box A, draw the arrangement of particles in a solid.
b. In box C, draw the arrangement of particles in a gas.
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