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Essential Chemistry for IGCSE - Particles And Purification (Section 8)

1
Why is it important to read a meniscus at eye level when measuring the volume of a liquid?
Answer
(B)
To prevent parallax error and obtain an accurate reading.
2
What is decanting used for?
Answer
(A)
To separate a solid from a liquid
3
What are the essential parts of a distillation setup?
Answer
A
B
D
4
What is true about a substance's purity?
Answer
A
C
D
5
Which of the following statements are true about the R_f value in chromatography?
Answer
A
B
D
6
Which state of matter has a definite volume but no definite shape?
Answer
(B)
Liquid
7
What are the common techniques for purifying a solid?
Answer
A
B
C
8
What does the R_f value in chromatography represent?
Answer
(B)
The ratio of the distance traveled by a substance to the distance traveled by the solvent front
9
What are the factors that contribute to the effectiveness of fractional distillation?
Answer
A
B
C
10
What method would be most suitable for separating ethanol and water?
Answer
(B)
Distillation
11
What are the essential components for performing simple distillation?
Answer
A
B
C
12
What is the expected result when separating a pure substance?
Answer
(C)
A sharp, well-defined melting point
13
What are some of the uses for chromatography?
Answer
A
B
C
14
What property of a substance can be used to determine its purity?
Answer
(C)
Melting point
15
In chromatography, what does the term 'mobile phase' refer to?
Answer
(B)
The solvent that moves through the chromatography system
16
In chromatography, what does the term 'stationary phase' refer to?
Answer
(B)
The substance that remains fixed and allows the separation.
17
What does the rate of diffusion depend upon?
Answer
A
B
D
18
What happens to the rate of diffusion as the temperature increases?
Answer
(B)
It increases.
19
What is the function of the baseline in paper chromatography?
Answer
A
C
D
20
What is happening to the energy of the particles as a substance boils?
Answer
(B)
Energy is increasing.
21
What does the R_f value help determine?
Answer
(B)
The identity of the components in a mixture
22
What is the correct unit for measuring mass?
Answer
(B)
Grams
23
When measuring a liquid's volume, where do you read the measurement?
Answer
(B)
At the bottom of the meniscus.
24
What is the relationship between temperature and the movement of particles?
Answer
(D)
As temperature increases, particle movement increases.
25
Which of the following pieces of equipment would you use to accurately measure 25.0 cm³ of a liquid?
Answer
(C)
A measuring cylinder
26
What is the principle behind solvent extraction?
Answer
(B)
Separation based on different solubilities in two immiscible solvents.
27
What is the fundamental principle behind fractional distillation?
Answer
(B)
Separation based on the different boiling points of liquids
28
In a fractional distillation setup, what is the role of the fractionating column?
Answer
(B)
To separate the liquids based on their boiling points
29
Which pieces of equipment are appropriate for volume measurement?
Answer
A
C
D
30
In paper chromatography, what factors influence the separation of a mixture?
Answer
A
B
D
31
What is the main purpose of the fractionating column in fractional distillation?
Answer
(B)
To facilitate the separation of liquids with close boiling points by increasing surface area.
32
What evidence supports the kinetic particle theory?
Answer
(A)
Diffusion
33
Which of the following statements describes diffusion?
Answer
(B)
The movement of particles from a high to low concentration.
34
When measuring a liquid, where should your eye be relative to the meniscus?
Answer
(C)
At the same level.
35
Which separation technique is based on differences in boiling points?
Answer
(C)
Distillation
36
Which term describes two liquids that do not mix with each other?
Answer
(D)
Immiscible
37
What can be used to remove a solid precipitate from a solution?
Answer
(B)
Filtration
38
What is the function of the thimble in the Soxhlet apparatus?
Answer
(A)
To contain the solid sample to be extracted
39
Which state of matter is characterized by a fixed shape and volume?
Answer
(A)
Solid
40
What is the definition of Brownian Motion?
Answer
(B)
The random movement of particles suspended in a fluid.
41
In paper chromatography, what is the stationary phase?
Answer
(B)
The paper
42
What are some correct units for measuring volume?
Answer
A
B
D
43
In the context of changing states, which of the following require energy input?
Answer
A
C
44
Which of the following best describes the arrangement of particles in a solid?
Answer
(B)
Closely packed, in a regular pattern, and vibrating in fixed positions.
45
What is the name for the change of state from liquid to solid?
Answer
(C)
Freezing
46
Which technique is used to separate a solid from a liquid?
Answer
(B)
Filtration
47
What happens to the speed of the molecules during a change of state
Answer
(C)
The speed remains constant.
48
Why does a gas exert pressure on the walls of its container?
Answer
(C)
Because the gas particles collide with the walls.
49
What is essential for a successful recrystallization process?
Answer
B
C
50
In a chromatography experiment, where does the solvent front run?
Answer
(B)
Towards the top of the paper or column