Essential Chemistry for IGCSE - Chemical Changes (Section 2)
1
What is the purpose of the electrolyte in an electrochemical cell?
پاسخ دهید(A)
To allow the flow of ions.
2
In a fuel cell, how does the hydrogen react at the negative electrode (anode) in an alkaline electrolyte?
3
What does 'H' represent in energy level diagrams?
4
What is a chemical change?
پاسخ دهید(C)
The formation of a new substance.
5
In a hydrogen fuel cell, what happens at the cathode?
پاسخ دهید(B)
Oxygen molecules are reduced.
6
What is the oxidation number of an atom in its elemental form?
7
What is the main advantage of using fuel cells?
پاسخ دهید(C)
They produce only water as a byproduct.
8
Which of the following are advantages of a fuel cell?
9
What does the difference between the energy of the reactants and the products represent?
10
What happens to the electrodes in an electrochemical cell as the cell runs?
پاسخ دهید(C)
The electrodes lose mass.
11
Which of the following is an example of a chemical change?
12
What does the 'activation energy' represent in a chemical reaction?
پاسخ دهید(B)
The minimum energy required for the reaction to start.
13
Which electrode is the site of oxidation in an electrochemical cell?
14
Which of the following is a characteristic of an exothermic reaction?
پاسخ دهید(C)
The temperature of the surroundings increases.
15
A reaction is exothermic if:
پاسخ دهید(C)
The reaction releases heat to the surroundings.
16
What is the function of the salt bridge in a galvanic cell?
پاسخ دهید(C)
To maintain charge balance in the half-cells.
17
Which of the following statements about the reactivity series is correct?
پاسخ دهید(A)
Metals higher in the series readily lose electrons.
18
Which of the following is true for an exothermic reaction?
19
Which of the following is a characteristic of a chemical change?
پاسخ دهید(C)
Formation of a new substance
20
What does the term 'bond energy' refer to?
پاسخ دهید(A)
The energy required to break one mole of a particular bond in one mole of gaseous atoms.
21
What is the role of a metal in an electrochemical cell?
22
What is the primary difference between an electrolytic cell and a fuel cell?
پاسخ دهید(A)
Electrolytic cells use electricity to drive chemical reactions, while fuel cells generate electricity from chemical reactions.
23
What is the main advantage of fuel cells over internal combustion engines?
پاسخ دهید(C)
They are more efficient and produce fewer emissions.
24
What is the main energy source used in a nuclear power station?
25
What is the main product of a hydrogen fuel cell?
26
What happens to energy during a physical change?
پاسخ دهید(D)
Energy may be absorbed or released.
27
In a simple electrochemical cell, which electrode is the site of oxidation?
28
Which of the following is not a product of a hydrogen fuel cell reaction?
29
In a hydrogen fuel cell, which electrode is the cathode, and what reaction occurs there?
پاسخ دهید(D)
Cathode, oxygen reduction
30
In a simple electrochemical cell, what direction do electrons flow?
پاسخ دهید(C)
From the anode to the cathode.
31
In a hydrogen fuel cell, which ion is the charge carrier in the acidic electrolyte?
32
Which of the following is the primary function of a battery?
پاسخ دهید(C)
To store and release electrical energy.
33
In a hydrogen fuel cell, which material is typically used as the electrolyte?
پاسخ دهید(B)
Aqueous solution of acid or alkali
34
In the context of fuel cells, what is the role of a catalyst?
35
What do all electrochemical cells have in common?
پاسخ دهید(A)
They involve oxidation and reduction reactions.
36
In a fuel cell, the reaction at the anode is:
37
What is the standard unit for bond energy?
پاسخ دهید(C)
Kilojoules per mole (kJ/mol)
38
What is a key feature of a fuel cell compared to a combustion engine?
39
What is the role of oxygen in a fuel cell?
پاسخ دهید(B)
It is the oxidizing agent.
40
What is the relationship between potential difference and electrochemical reactions?
41
What type of energy is primarily converted into electrical energy in a fuel cell?
42
Which of the following statements are correct about the comparison of chemical changes and physical changes?
43
In a simple electrochemical cell, which electrode is the site of reduction?
44
If a reaction is endothermic, what can be said about the energy of the products versus the reactants?
پاسخ دهید(C)
The products have more energy.
45
Which of the following is a characteristic of an acidic electrolyte in a fuel cell?
پاسخ دهید(A)
The hydrogen ions move through the electrolyte.
46
What is the function of the electrodes in an electrochemical cell?
پاسخ دهید(C)
To be the site of oxidation and reduction reactions.
47
پاسخ دهید(B)
A substance that releases energy when it burns.
48
If a reaction has a positive enthalpy change (ΔH), what type of reaction is it?
49
In a chemical reaction, if the energy of the reactants is higher than the energy of the products, what type of reaction is it?
50
What are the main reactants in a hydrogen fuel cell?
