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Essential Chemistry for IGCSE - Particles And Purification (Section 3)

1
Which of the following is NOT a method of purification?
Answer
(D)
Dissolving
2
In paper chromatography, which of these materials acts as the stationary phase?
Answer
(B)
The paper
3
Which state of matter is described by the properties: definite volume, but not definite shape?
Answer
(B)
Liquid
4
What does the 'R_f' value represent in paper chromatography?
Answer
(B)
The ratio of the distance traveled by the solute to the distance traveled by the solvent
5
During the process of freezing, what happens to the energy of the substance?
Answer
(B)
The energy is released.
6
Which of the following is used to separate a mixture of two or more liquids with different boiling points?
Answer
(B)
Distillation
7
Which of the following is/are necessary for a measurement to be considered accurate?
Answer
A
D
8
Which of these is a property that could be used to distinguish between two different substances?
Answer
A
C
9
Which of these techniques relies on differences in boiling points to separate a mixture?
Answer
(C)
Distillation
10
What is the main difference between a physical and a chemical change?
Answer
(B)
Chemical changes involve a change in the chemical composition of a substance.
11
Which methods can be used to purify a substance?
Answer
B
C
D
12
Which of the following methods is used to separate a solid from a liquid?
Answer
(C)
Filtration
13
What happens during the process of condensation?
Answer
(B)
Particles lose energy, and the gas becomes a liquid.
14
What would you measure to calculate the density of a regularly shaped solid object?
Answer
(B)
Volume by calculation and mass with a balance.
15
Which of the following is an endothermic process?
Answer
B
C
16
Which methods can be used to purify a solid substance?
Answer
B
C
17
What is the purpose of the R_f value in paper chromatography?
Answer
A
C
18
What can be used to remove insoluble solid impurities from a liquid?
Answer
(A)
Filtration
19
What does the solvent do in the paper chromatography?
Answer
(C)
Carries the sample through the paper.
20
When a substance changes state, what always occurs?
Answer
(D)
A change in energy
21
How are substances separated in fractional distillation?
Answer
(B)
By their boiling points
22
Which technique would you use to separate a solution of salt water?
Answer
A
D
23
Which process involves the change of state from liquid to solid?
Answer
(D)
Freezing
24
Which state of matter has the most kinetic energy?
Answer
(C)
Gas
25
Which of the following best describes the behavior of gas particles?
Answer
(C)
Far apart, constantly moving and colliding.
26
Which of the following processes involves a change of state?
Answer
(B)
Evaporation
27
Which method separates a solid from a liquid by using evaporation?
Answer
(D)
Evaporation
28
What is the first step in paper chromatography?
Answer
A
C
29
What is the term for the change of state from a solid directly to a gas?
Answer
(C)
Sublimation
30
During which change of state does a substance release energy?
Answer
B
D
31
How does crystallization work?
Answer
(C)
Allowing a solution to cool so that a solid forms crystals
32
What is the function of the filter paper in filtration?
Answer
(B)
To trap the solid particles
33
How does increasing the temperature of a substance affect the kinetic energy of its particles?
Answer
(C)
It increases the kinetic energy.
34
During which phase change do particles lose energy?
Answer
B
D
35
Which is not used for the purification of solids?
Answer
(A)
Distillation
36
What type of particles are involved in Brownian motion?
Answer
(B)
Small particles
37
What type of apparatus would you use to measure 20.0 cm³ of a liquid?
Answer
(B)
A measuring cylinder
38
How can the purity of a substance be determined?
Answer
(B)
By measuring its melting point or boiling point
39
Which of the following conditions will increase the rate of diffusion?
Answer
A
C
40
Which of the following is a method of purification?
Answer
(D)
All of the above
41
What is the function of the condenser in distillation?
Answer
(B)
To cool and condense the vapor
42
What information is obtained from a chromatogram?
Answer
A
B
D
43
What is the main difference between evaporation and boiling?
Answer
(B)
Evaporation occurs only on the surface of a liquid, while boiling occurs throughout the liquid.
44
What is a key indicator that a substance is pure?
Answer
(B)
A sharp melting point.
45
What factors affect how far a substance moves in paper chromatography?
Answer
A
D
46
Why is a pure substance important in the pharmaceutical industry?
Answer
(D)
All of the above
47
Impurities in a substance can affect its:
Answer
(C)
Both melting and boiling points
48
Which of the following is an example of a chemical change?
Answer
(C)
Burning wood.
49
What is the most likely effect of an impurity on a substance's boiling point?
Answer
(C)
It will broaden the boiling point range.
50
What happens to the kinetic energy of particles during a phase change?
Answer
(C)
Kinetic energy remains constant.