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Essential Chemistry for IGCSE - Particles And Purification (Section 10)

1
What is the name of the process of separating a solid from a solution by cooling it and allowing crystals to form?
Answer
(C)
Crystallization
2
What would happen to the boiling point of water if salt was dissolved in it?
Answer
(C)
It would increase
3
What is used to heat and vaporize the liquid in a simple distillation?
Answer
(B)
A Bunsen burner or heating mantle
4
What is the basis for separating compounds in chromatography?
Answer
(C)
Differences in their interaction with the mobile and stationary phases.
5
In paper chromatography, what is the solvent front?
Answer
(A)
The leading edge of the solvent as it moves up the paper
6
Which property of a substance changes during the phase transition from a solid to a liquid?
Answer
(B)
Melting point
7
What happens to the melting point of a substance when impurities are present?
Answer
(B)
The melting point decreases.
8
Which of the following best describes the movement of particles in a liquid?
Answer
(B)
Moving randomly, sliding past each other.
9
Which of these can be used to measure volume?
Answer
B
C
10
What is the main purpose of a Soxhlet extractor?
Answer
(B)
To continuously extract a compound from a solid with a solvent.
11
What is the main aim of recrystallization?
Answer
(C)
To obtain a pure solid from an impure one.
12
During boiling, what happens to the temperature of the liquid?
Answer
(C)
It remains constant.
13
How are particles arranged in a gas?
Answer
(C)
Randomly arranged and far apart.
14
Which technique would be best used to separate salt from sand?
Answer
(C)
Filtration, followed by evaporation
15
What is the purpose of the condenser in a distillation setup?
Answer
(B)
To cool and condense vapors into a liquid
16
How is the rate of diffusion affected by temperature?
Answer
(A)
It increases with increasing temperature.
17
What is the underlying principle behind purification techniques?
Answer
(B)
Separating a compound from undesired components based on their physical or chemical properties.
18
What is the role of kinetic energy in diffusion?
Answer
(B)
It is the driving force behind diffusion.
19
What is the function of a drying agent in a purification process?
Answer
(A)
To remove water or moisture
20
What does Brownian motion provide evidence for?
Answer
(B)
The motion of particles.
21
Which of the following are used for separating a mixture?
Answer
A
B
C
22
Which of these factors primarily determines the boiling point of a liquid?
Answer
(C)
Its molecular weight and intermolecular forces
23
Which factors affect the separation of compounds using paper chromatography?
Answer
A
B
C
24
What is the effect of increasing the surface area on the rate of evaporation?
Answer
(A)
The rate of evaporation increases.
25
What happens to the pressure of a gas if you decrease the container's volume while keeping the temperature constant?
Answer
(B)
Pressure increases.
26
Which of the following is not a method of purification?
Answer
(D)
Mixing
27
What is the role of the stationary phase in chromatography?
Answer
(B)
To separate the sample components based on their properties
28
How can you explain the observation of Brownian motion?
Answer
(B)
The random movement of larger particles due to collisions with smaller, invisible particles.
29
Which of the following is the best definition for melting point?
Answer
(A)
The temperature at which a solid changes to a liquid.
30
What are the limitations of simple distillation?
Answer
A
C
31
If a substance is heated, what happens to the forces of attraction between the particles?
Answer
(B)
The forces of attraction decrease.
32
What is the relationship between molecular mass and the rate of diffusion?
Answer
(B)
Lighter molecules diffuse faster.
33
What factors affect the rate of diffusion of a gas?
Answer
A
B
C
34
Which methods can be used for separating mixtures?
Answer
A
B
C
35
What is the primary purpose of the fractionating column in a fractional distillation apparatus?
Answer
(B)
To increase the surface area for condensation and re-evaporation
36
Which method is best to separate the pigment found in ink?
Answer
(C)
Paper chromatography
37
What does 'immiscible' mean in the context of liquids?
Answer
(B)
Not mixable
38
What is the main advantage of fractional distillation compared to simple distillation?
Answer
(B)
It separates liquids with very similar boiling points
39
What is the name of the process where a solid changes directly into a gas?
Answer
(C)
Sublimation
40
Which of the following is NOT a way to identify a substance's purity?
Answer
(D)
Color change upon heating
41
In the context of chemical purity, what does a narrow melting point range indicate?
Answer
(B)
The substance is pure
42
Which of the following characteristics describe ideal solvents for recrystallization?
Answer
A
C
43
In which state of matter do the particles have the weakest forces of attraction?
Answer
(C)
Gas
44
What is the process of obtaining crystals from a solution called?
Answer
(C)
Crystallization
45
In simple distillation, what does the condenser do?
Answer
(B)
Cools the vapor back into a liquid
46
Why is it important to use a slow rate of heating during crystallization?
Answer
(B)
To allow the crystals to form slowly and grow larger
47
What happens to the particles of a gas as they diffuse?
Answer
(C)
They spread out and mix with other particles.
48
Which of the following are states of matter?
Answer
A
B
C
D