Sign In

Essential Chemistry for IGCSE - Chemical Changes (Section 3)

1
What are the components needed for a simple electrochemical cell?
Answer
A
B
C
2
Which statement is true regarding the energy change in an exothermic reaction?
Answer
(C)
The enthalpy change (ΔH) is negative.
3
Which of the following is a key advantage of using fuel cells over traditional combustion engines in vehicles?
Answer
(A)
Higher efficiency
4
What happens to the temperature of the surroundings during an exothermic reaction?
Answer
(B)
It increases.
5
What are some major contributors to acid rain?
Answer
A
B
6
What is the primary output of a hydrogen fuel cell?
Answer
(A)
Water
7
What type of fuel releases the least amount of greenhouse gases when burned?
Answer
(C)
Natural gas
8
What is the purpose of the electrolyte in an electrochemical cell?
Answer
(B)
To allow ion movement
9
What is the function of the electrolyte in an electrochemical cell?
Answer
(C)
To allow ion flow.
10
Why are hydrogen fuel cells considered a cleaner energy source than gasoline-powered vehicles?
Answer
(B)
Fuel cells produce only water.
11
The energy level diagram for an exothermic reaction shows that the products have:
Answer
(B)
Lower energy than the reactants.
12
In the context of energy level diagrams, what do the arrows represent?
Answer
(B)
The direction of energy transfer
13
Which of the following best describes the overall reaction that occurs in a fuel cell?
Answer
(C)
Direct conversion of chemical energy to electrical energy
14
In a nuclear power plant, what material undergoes nuclear fission?
Answer
(C)
Uranium
15
What is the function of the electrolyte in a fuel cell?
Answer
(B)
To facilitate ion movement.
16
What type of reaction is bond formation typically?
Answer
(A)
Exothermic
17
What is the relationship between energy and an endothermic reaction?
Answer
(B)
Energy is absorbed.
18
Which of these components controls the nuclear reaction in a reactor?
Answer
(B)
Control rods
19
Which of the following is a key advantage of fuel cells compared to batteries?
Answer
(B)
They have a higher energy density.
20
What environmental problem is linked to the use of fossil fuels?
Answer
(B)
Air pollution
21
What is the primary function of control rods in a nuclear reactor?
Answer
(B)
To absorb neutrons.
22
What is a defining characteristic of fossil fuels?
Answer
(B)
They are formed from the remains of ancient organisms.
23
What are the electrode types in a fuel cell?
Answer
(A)
Anode and cathode
24
Which of the following is a major role of a nuclear reactor's coolant?
Answer
(C)
To remove heat.
25
What does a positive value for ΔH indicate?
Answer
(B)
An endothermic reaction
26
What happens to electrons in oxidation?
Answer
(B)
They are lost.
27
In general, what type of reaction is bond breaking?
Answer
(B)
Endothermic
28
Which of the following is a characteristic of a chemical change?
Answer
(B)
Formation of a new substance
29
What occurs at the anode in an electrochemical cell?
Answer
(B)
Oxidation
30
Where does reduction take place in a fuel cell?
Answer
(B)
Cathode
31
What is the primary role of the control rods in a nuclear reactor?
Answer
(B)
To absorb neutrons.
32
What is the best definition of a chemical change?
Answer
(B)
A change that produces new substances with different properties
33
What does an electrochemical cell do?
Answer
(A)
Converts chemical energy to electrical energy.
34
Which of the following is an example of a physical change?
Answer
(C)
Melting ice
35
What process occurs at the anode of a fuel cell?
Answer
(A)
Oxidation
36
Which of the following reactions is characterized by a negative ΔH value?
Answer
(B)
An exothermic reaction
37
In an exothermic reaction, what happens to the surroundings?
Answer
(B)
They release heat.
38
What is a major environmental consequence of burning fossil fuels?
Answer
(B)
Release of greenhouse gases.
39
Which of the following is a key characteristic of a hydrogen fuel cell?
Answer
(B)
Produces no pollution (water only)
40
In a fuel cell, oxygen is involved at which electrode?
Answer
(B)
Cathode
41
Which substance is commonly used as a fuel source in nuclear power plants?
Answer
(C)
Uranium
42
Which process involves the formation of new substances?
Answer
(B)
Chemical change
43
What is one advantage of hydrogen fuel cells?
Answer
(B)
Produces water as waste
44
What is a fuel?
Answer
(B)
A substance that releases energy when burned.
45
Which factor primarily determines the amount of energy released or absorbed during a chemical reaction?
Answer
(B)
The enthalpy change (ΔH)
46
What is a key component of both coal and natural gas?
Answer
(B)
Carbon
47
What is the primary function of a nuclear reactor's coolant?
Answer
(D)
To remove heat
48
What sign is typically used to represent the enthalpy change (ΔH) in an exothermic reaction?
Answer
(B)
Negative
49
Which is the other electrode of a fuel cell?
Answer
(A)
Anode
50
What does a negative value for ΔH indicate?
Answer
(B)
An exothermic reaction