Essential Chemistry for IGCSE - Particles And Purification (Section 6)
1
What is the purpose of using a distillation apparatus?
Answer
(D)
All of the above
2
In which state of matter do particles have the most kinetic energy?
Answer
(C)
Gas
3
Which of the following is a purification technique involving dissolving a solid in a hot solvent and then cooling the solution to obtain pure crystals?
Answer
(D)
Recrystallization
4
What is the relationship between the kinetic energy of gas particles and their temperature?
Answer
(B)
Kinetic energy decreases with decreasing temperature.
5
Which of the following statements about measuring volumes is correct?
Answer
A
C
6
Why does a gas expand to fill its container?
Answer
(C)
The gas particles are in constant random motion.
7
What are the key characteristics of a substance's melting point?
Answer
A
B
D
8
According to the kinetic particle theory, what happens to the particles when a substance is heated?
Answer
(C)
The particles' movement speed increases.
9
Which term describes the phase change from gas to solid?
Answer
(C)
Deposition
10
In paper chromatography, why are the sample spots made small and concentrated?
Answer
(B)
To ensure better separation
11
If you have two gases at the same temperature, what happens to their rate of diffusion?
Answer
(B)
The gas with the lighter molecules diffuses faster.
12
What is the main difference between the rate of diffusion in liquids and gases?
Answer
(B)
Diffusion is faster in gases.
13
What is the significance of Brownian motion?
Answer
(B)
It shows that particles are in constant motion.
14
What is a key difference between solids and liquids in terms of particle arrangement?
Answer
(B)
Solids have a regular pattern, liquids do not.
15
What determines the state of matter of a substance?
Answer
(B)
The energy of its particles and the forces between them.
16
What is the purpose of allowing the solvent to run to the top in paper chromatography?
Answer
(C)
To fully separate the components.
17
What is the role of the thermometer?
Answer
(C)
To measure the temperature of the liquid.
18
What is the function of the condenser in a distillation apparatus?
Answer
(B)
To cool and condense the vapor.
19
Which statement best describes the concept of the solvent front?
Answer
(B)
The leading edge of the mobile phase during chromatography.
20
Which technique is best for separating liquids with different boiling points?
Answer
(C)
Fractional distillation
21
What is the term for a liquid that dissolves a solute?
Answer
(C)
Solvent
22
Which of the following statements is/are true regarding the arrangement of particles in a solid?
Answer
B
C
23
What does the term 'diffusion' describe?
Answer
(B)
The movement of particles from an area of high concentration to low concentration.
24
In which state of matter do particles move the most freely?
Answer
(C)
Gas
25
What happens to the melting point of a pure solid when it contains impurities?
Answer
(B)
Decreases and broadens
26
Which of the following are methods of determining the purity of a substance?
Answer
A
B
C
27
What will happen to the melting point of a pure substance if it is contaminated with an impurity?
Answer
(B)
It will decrease
28
What is a graduated cylinder used for?
Answer
(B)
To measure the volume of liquids.
29
What happens to the particles of a gas if you compress it?
Answer
(C)
They get closer together.
30
Which of the following affects the rate of diffusion?
Answer
A
B
D
31
How does a higher molecular mass affect the rate of diffusion?
Answer
(B)
Higher molecular mass means slower diffusion.
32
What happens to the particles' speed during a phase change (e.g., melting)?
Answer
(C)
The speed remains constant.
33
What is the purpose of the spotting line (baseline) in paper chromatography?
Answer
(B)
To mark the starting points of the sample spots.
34
What must you make sure you are doing, when measuring a volume?
Answer
(A)
Eye level with the meniscus
35
What is the main purpose of the mobile phase in chromatography?
Answer
(B)
To carry the sample components through the stationary phase.
36
What instrument do you use to take accurate measurements of liquids?
Answer
(B)
Pipette.
37
What is the purpose of a fractionating column in fractional distillation?
Answer
(A)
To provide a larger surface area for condensation and re-evaporation.
38
In a gas, what happens to the particle movement when you increase the temperature?
Answer
(D)
The movement speeds up.
39
Which of the following are important features of a good solvent for recrystallization?
Answer
A
B
40
What phase change is the opposite of evaporation?
Answer
(C)
Condensation
41
What is a key indicator of a pure substance?
Answer
(B)
A sharp, defined melting point
42
In the context of chemical purity, what is a 'trace' impurity?
Answer
(B)
A tiny amount of an undesired substance in the sample.
43
How is the retention factor (R_f) value calculated?
Answer
(B)
Distance traveled by the solute / Distance traveled by the solvent
44
In paper chromatography, what is the purpose of allowing the solvent to run to the top of the paper?
Answer
(A)
To ensure complete separation of the components
45
What does the term "elution" refer to in chromatography?
Answer
(B)
The process of moving the components through the stationary phase with a solvent
46
Which of the following is the best technique to separate a mixture of two miscible liquids with significantly different boiling points?
Answer
(B)
Simple distillation
47
What is the correct order of the steps in paper chromatography?
Answer
(A)
Spot the sample, develop the chromatogram, dry the paper, measure the R_f value
48
In which state of matter does diffusion occur most rapidly?
Answer
(C)
Gas
49
What is the main driving force behind diffusion?
Answer
(C)
Concentration gradients
50
Which measuring instrument is most accurate for measuring volumes of liquids?
