Sign In

Essential Chemistry for IGCSE - Particles And Purification (Section 9)

1
Which of the following is a key step in crystallization?
Answer
(C)
Slow evaporation of the solvent
2
Which method is used for separating two or more liquids that are miscible?
Answer
(C)
Distillation
3
What is the role of the mobile phase in chromatography?
Answer
(B)
To carry the sample components through the stationary phase.
4
What is the standard unit of mass?
Answer
(C)
Grams
5
During a phase change, what kind of energy is changing in the particles?
Answer
(B)
Potential energy.
6
What is the function of the condenser in distillation?
Answer
(B)
To cool the vapors and convert them back to liquid
7
Which of the following factors affect the separation in paper chromatography?
Answer
A
B
C
8
Which factors does the speed of diffusion depend on?
Answer
A
B
C
9
In the context of diffusion, what does a 'higher concentration' of a substance mean?
Answer
(A)
More particles of the substance are present.
10
What happens to the forces of attraction between particles during melting?
Answer
(B)
Forces of attraction decrease.
11
What does the term 'meniscus' refer to when measuring liquids?
Answer
(B)
The curved surface of the liquid.
12
How can you distinguish the three states of matter?
Answer
A
B
13
What is the primary reason why diffusion occurs?
Answer
(B)
Particles are constantly moving and colliding.
14
Which of the following are methods used in purification of a substance?
Answer
A
B
C
15
Which factors influence the rate of evaporation?
Answer
A
B
C
16
Which of the following techniques could be used to separate sand from water?
Answer
(B)
Filtration
17
What term refers to the change of state from liquid to gas?
Answer
(C)
Evaporation
18
What type of apparatus is best suited for measuring gas volumes?
Answer
(B)
A gas syringe
19
What does a narrow melting point range typically indicate about a substance?
Answer
(C)
The substance is pure
20
What is the purpose of using a separating funnel?
Answer
(B)
To separate two immiscible liquids
21
What are the particles in a liquid attracted to?
Answer
(C)
Both each other and the container.
22
Which type of distillation is used to separate liquids with boiling points that are close together?
Answer
(C)
Fractional distillation
23
What is the name of the process by which a solid changes directly into a gas?
Answer
(C)
Sublimation
24
Which of the following is most likely to diffuse fastest?
Answer
(C)
Ammonia at 25°C
25
What happens to the volume of a fixed amount of gas when its temperature increases?
Answer
(B)
The volume increases.
26
What can be said about the particles of a liquid compared to a gas?
Answer
(A)
Liquid particles have less energy.
27
Which of the following is a key characteristic of the kinetic particle theory?
Answer
(B)
Particles in a substance are in constant motion.
28
What should you do to a mixture of salt and water to get pure salt back?
Answer
(A)
Evaporate the water.
29
What happens during condensation?
Answer
(C)
A gas turns into a liquid.
30
Which is the most accurate way to measure a volume?
Answer
(C)
Using a pipette.
31
Which factors affect the rate of evaporation?
Answer
A
B
C
32
When should you read the meniscus of a liquid correctly?
Answer
(B)
At the bottom of the curve
33
Which of the following statements best describes Brownian motion?
Answer
(B)
The random movement of small particles suspended in a liquid or gas.
34
What does the Kinetic Particle Theory not state?
Answer
(C)
The particles are always the same.
35
Impurities in a substance can lead to what effect on the melting point?
Answer
(B)
Decrease
36
Which of these processes is involved in recrystallization?
Answer
(C)
Cooling a saturated solution to induce crystal formation.
37
What is the correct order for the steps involved in recrystallization?
Answer
A
B
C
D
38
What are the important steps for recrystallization?
Answer
A
B
C
39
What happens when the rate of evaporation equals the rate of condensation?
Answer
(B)
The substance reaches equilibrium.
40
Which of the following are methods of purification?
Answer
A
B
C
41
What is the role of a drying agent?
Answer
(A)
To remove moisture.
42
What would be the best method to separate a solid from a liquid when the solid is insoluble?
Answer
(D)
Filtration
43
What causes the random movement of particles in Brownian motion?
Answer
(B)
Collisions with other particles.
44
What are the correct units for measuring volume?
Answer
A
C
D
45
In paper chromatography, what is used to visualize the separated components?
Answer
(B)
A developing agent or UV light
46
In a solid, how do the particles move?
Answer
(B)
They vibrate in fixed positions.
47
What is the relationship between temperature and particle kinetic energy?
Answer
(C)
As temperature increases, kinetic energy increases.
48
In a distillation, which substance will typically distill over first?
Answer
(B)
The substance with the lowest boiling point.
49
Which of the following is an example of a physical change?
Answer
(C)
Melting ice.
50
What is the purpose of the water inlet and outlet in a condenser during distillation?
Answer
(B)
To keep the condenser cool, enabling condensation of the vapors