Download Multiple-choice questions : 1. Which of the following combinations is

Multiple-choice questions :
1.
Which of the following combinations is correct?
Type of cell
Positive electrode
Negative electrode
A.
Zinc-carbon cell
Zinc
Graphite
B.
Alkaline manganese cell
Manganese(IV) oxide
Zinc
C.
Silver oxide cell
Zinc oxide
Silver
D.
Zinc-carbon cell
Ammonium chloride
Graphite
□
2.
Which of the following statements about an alkaline manganese cell are
INCORRECT?
(1) The cell is rechargeable.
(2) The cell contains ammonium chloride as the electrolyte.
(3)
A.
B.
C.
D.
The new cell gives a voltage of 1.25 V.
(1) and (2) only
(1) and (3) only
(2) and (3) only
(1), (2) and (3)
□
3.
Which of the following statements concerning a silver oxide cell is correct?
A. The voltage falls rapidly over discharge.
B. The negative electrode of the cell is a mixture of powdered graphite and
silver oxide.
C. The charge capacity is greater than that of a zinc-carbon cell.
D. The electrolyte in the cell is potassium hydroxide.
□
4.
Which of the following metals loses electrons most readily (to form cations) in
an aqueous solution?
A. Magnesium
B.
C.
D.
Lead
Sodium
Potassium
□
1
5.
Consider the simple chemical cell shown below.
connecting wires
lead electrode
magnesium
electrode
lemon
Which of the following statements are correct?
(1) Magnesium electrode is the negative electrode.
(2) Hydrogen gas is evolved at the lead electrode.
(3)
A.
B.
C.
D.
Electrons flow from magnesium electrode to lead electrode in the lemon.
(1) and (2) only
(1) and (3) only
(2) and (3) only
(1), (2) and (3)
□
6.
Consider the simple chemical cell shown below.
electrode Y
electrode X
electrolyte
Which of the following combinations is correct?
Electrode X
Electrode Y
A.
Copper
Copper
B.
Silver
Copper
C.
Zinc
Copper
D.
Plastic rod
Copper
□
2
7.
Which of the following equations is correct for the reactions taking place in the
chemical cell as shown below?
bulb lights
magnesium electrode
copper electrode
sodium chloride
solution
A.
B.
C.
D.
Mg(s)  Mg2+(aq) + 2e
Cu(s)  Cu2+(aq) + 2e
Na+(aq) + e  Na(s)
2Cl(aq)  Cl2(g) + 2e
□
8.
Metal X is higher than metal Y in the Electrochemical Series. Which of the
following statements is INCORRECT?
A. In most cases, X should be more reactive than Y.
B. X loses electrons to form cations in aqueous solution more readily than Y.
C.
D.
The further apart X and Y are in the series, the greater is the voltage of the
chemical cell formed using the two metals.
Y is the negative pole in the chemical cell with the metal couple X/Y.
□
9.
Which of the following statements about the Electrochemical Series are correct?
(1) The positions of metals in the Electrochemical Series are identical with that
in the metal reactivity series.
(2) It arranges metals according to their tendencies to lose electrons.
(3) For a simple chemical cell consisting of two different metals and an
A.
B.
C.
D.
electrolyte, the further apart the two metals are in the Electrochemical
Series, the higher is the voltage of the cell.
(1) and (2) only
(1) and (3) only
(2) and (3) only
(1), (2) and (3)
□
3
10. Consider the simple chemical cell shown below.
digital multimeter
(as voltmeter)
electrode Q
electrode P
sodium chloride solution
Which of the following pairs of metals will produce the largest voltage?
Electrode P
Electrode Q
A.
Iron
Zinc
B.
Magnesium
Copper
C.
Magnesium
Iron
D.
Copper
Iron
□
11. Consider the simple chemical cell shown below.
iron electrode
magnesium electrode
sodium chloride
solution
Which of the following changes would lead to an increase in the voltage of the
cell?
(1) The magnesium electrode is replaced by a zinc electrode.
(2) The iron electrode is replaced by a copper electrode.
(3) The sodium chloride solution is replaced by ethanol.
A. (1) only
B. (2) only
C. (1) and (3) only
D. (2) and (3) only
4
□
12. Consider the following set-up:
digital multimeter
(as voltmeter)
filter paper
soaked in
NaCl(aq)
another metal foil
copper foil
plastic sheet
In an experiment, the tendency of four metals W, X, Y and Z to lose electrons in
aqueous solution are compared. In each case, the voltmeter reading was recorded.
The results were tabulated as follows:
Metal under test
Direction of electron flow in
the external circuit
Voltage recorded (volts)
W
W to Cu
+0.79
X
Cu to X
0.22
Y
Y to Cu
+1.41
Z
Z to Cu
+0.20
Which of the following represents the decreasing order of tendency to lose
electrons (in aqueous solution) of the metals?
A. X > Y > Z > W
B. W > X > Z > Y
C. Y > W > Z > X
D. Z > W > X > Y
□
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13. Which of the following statements concerning salt bridge are correct?
(1) It completes the circuit by allowing ions to move from one half-cell into the
other.
(2) It provides ions to balance the charges in the solutions of the two half-cells.
(3) It allows electrons to flow from one electrode to the other electrode.
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
□
14. Consider the simple chemical cell shown below.
digital multimeter
(as voltmeter)
copper electrode
zinc electrode
salt
copper(II) sulphate
solution
bridge
zinc sulphate
solution
Which of the following statements are correct?
(1) The mass of the copper electrode increases.
(2) The filter paper acts as a salt bridge.
(3) Electrons flow from zinc electrode to copper electrode through the external
circuit.
A. (1) and (2) only
B. (1) and (3) only
C.
D.
(2) and (3) only
(1), (2) and (3)
□
6
15. Consider the following set-up:
digital multimeter
(as voltmeter)
copper electrode
zinc electrode
salt
bridge
zinc sulphate
solution
copper(II) sulphate
solution
Which of the following statements concerning the above set-up is correct?
A.
B.
C.
D.
Electrons flow from zinc electrode to copper electrode through the salt
bridge.
The copper electrode loses electrons.
The concentration of copper(II) ions increases.
The zinc electrode is the negative electrode.
□
16. Consider the following set-up:
copper electrode
zinc electrode
sodium chloride solution
After the cell operates, its voltage drops quickly. It is because
A.
B.
C.
D.
zinc electrode dissolves gradually in sodium chloride solution.
hydrogen gas evolved at the zinc and copper electrodes stops the reaction.
a thin layer of oxide is formed on the copper electrode.
the hydrogen ions in the sodium chloride solution have been used up.
□
7
17. Consider the simple chemical cell shown below.
zinc electrode
copper electrode
dilute hydrochloric
acid
Which of the following would NOT occur?
A.
B.
C.
Copper electrode would react with dilute hydrochloric acid.
Zinc electrode would react with dilute hydrochloric acid.
A gas is evolved at the zinc electrode.
D.
A gas is evolved at the copper electrode.
□
18. Consider the simple chemical cell shown below.
digital multimeter
(as voltmeter)
zinc electrode
1 M zinc sulphate
solution
lead electrode
salt
bridge
P
Q
1 M lead(II)
nitrate solution
Which of the following statements about the cell is/are correct?
(1) Lead metal deposits on the lead electrode.
(2)
(3)
A.
B.
C.
D.
The concentration of zinc ions increases in half-cell P.
Salt bridge allows electrons to flow from one half-cell into the other.
(1) and (2) only
(1) and (3) only
(2) and (3) only
(1), (2) and (3)
□
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19. Which of the following statements about salt bridge is INCORRECT?
A. It completes the circuit of a simple chemical cell.
B. It allows ions to move from one half-cell into the other.
C. It provides ions to balance the charges in the solutions of the two half-cells.
D. Silver chloride solution can be used to make a salt bridge.
□
20. In an experiment, a copper rod and an iron rod are dipped into dilute sulphuric
acid, with their top ends touching each other. Hydrogen bubbles are found
around the copper rod.
iron rod
copper rod
hydrogen
dilute sulphuric
acid
gas bubbles
Which of the following statements about the experiment is correct?
A. Electrons flow from copper rod to iron rod.
B. The iron rod becomes coated with copper.
C. Iron is more reactive than copper.
D.
Copper reacts with the acid.
□
9
Each question below consists of two separate statements. Decide whether each of
the two statements is true or false; if both are true, then decide whether or not
the second statement is a correct explanation of the first statement. Then select
one option from A to D according to the following table:
A. Both statements are true and the 2nd statement is a correct explanation
of the 1st statement.
B. Both statements are true and the 2nd statement is NOT a correct
explanation of the 1st statement.
C. The 1st statement is false but the 2nd statement is true.
D. Both statements are false.
21.
If an iron/copper metal couple is used
as electrodes in a simple chemical cell,
electrons flow from iron to copper
through the external circuit.
Iron is the negative electrode of this
cell.
□
22.
In the Cu/Ag chemical cell, copper is
the negative pole.
Copper loses electrons more readily
than silver.
□
23.
A salt bridge used to complete the
circuit by joining the two half-cells of a
chemical cell.
Salt bridge helps to maintain electrical
neutrality of the two half-cells.
□
24.
A simple chemical cell can be set up by
putting two different metals in an
electrolyte. The two metals are
Electrons flow from the more reactive
metal to the less reactive metal through
the external wire in the simple chemical
connected by an external wire.
cell.
□
10
Conventional questions :
1.
You are given the following information on the four dry cells of a certain brand:
Dry cell
W
X
Y
Z
Ability to supply a
large current?
No
No
Yes
Yes
Service life
Long
Short
?
Long
Rechargeable or not?
No
No
Yes
No
(a) Suggest which of the above cells could be a/an
(i) zinc-carbon cell.
(ii) alkaline manganese cell.
(iii) silver oxide cell.
(b) Which of the above cells is a secondary cell? Explain your answer.
(c) Suggest a daily use of a/an
(i) zinc-carbon cell.
(ii) alkaline manganese cell.
(iii) silver oxide cell.
[8M]
11
2.
Consider the simple chemical cell shown below.
zinc electrode
copper electrode
0.1 M sulphuric
acid
(a) State the direction of electron flow in the external circuit of the cell.
(b) Which is the positive electrode of the chemical cell?
(c) Suppose 0.2 M sulphuric acid is used as the electrolyte instead, what would
happen to the reading of the ammeter in the circuit? Explain your answer.
(d) Suppose 0.1 M ethanoic acid is used as the electrolyte instead. What would
happen to the reading of the ammeter in the circuit? Explain your answer.
[7M]
12
3.
Consider the simple chemical cell shown below.
connecting wires
lead electrode
zinc electrode
lemon
(a) State the direction of electron flow in the external circuit of the cell.
(b) Which is the negative electrode of the cell?
(c) Write an ionic half equation for the reaction taking place at zinc electrode.
(d) What would happen to the reading of the voltmeter if the lemon is replaced
by a beaker of sugar solution? Explain your answer.
[5M]
4.
Consider the following simple chemical cell. It consists of two different metal
electrodes (X and Y) and an electrolyte.
electrode X
electrode Y
sodium chloride solution
For each of the following metal couple in the table, write down the direction of
electron flow through the voltmeter.
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Electrode X
Electrode Y
(a)
Lead
Iron
(b)
Zinc
Magnesium
(c)
Iron
Aluminium
5.
Direction of electron flow
through the voltmeter
The following figure shows a simple chemical cell made from a lemon.
X
electrode
electrode
lemon
(a) What piece of equipment could be placed in the circuit at point ‘X’ to show
that the cell can produce electricity?
(b) The list below names a number of metals which could be used as the
electrodes for the cell.
(i)
(ii)
zinc, copper, iron, silver, magnesium, lead
Name the metal couple that should be used to give the highest voltage.
What voltage would be produced if both electrodes were made of
copper?
(c) Lemon juice contains the electrolyte citric acid.
(i) What is meant by an ‘electrolyte’?
(ii) Can an orange or a grapefruit be used instead of a lemon in this
experiment?
[5M]
14
6.
Consider the simple chemical cell shown below.
digital multimeter
(as voltmeter)
iron electrode
magnesium electrode
magnesium
sulphate solution
salt
bridge
iron(II) sulphate
solution
(a) Write a half equation for the reaction occurring at the magnesium electrode.
(b) Write a half equation for the reaction occurring at the iron electrode.
(c) State the direction of electron flow in the external circuit of the cell.
(d) Briefly describe any observable changes in
(i) magnesium half-cell.
(ii) iron half-cell.
(e) State the main functions of the salt bridge.
(f) What would happen if the piece of filter paper is removed from the above
set-up? Explain.
15
[10M]
7.
Consider the simple chemical cell shown below.
digital multimeter
(as voltmeter)
flow of electrons
metal Y
electrode
metal X
electrode
sulphate solution
of metal X
salt
bridge
nitrate solution
of metal Y
(a) Which metal is more reactive, X or Y? Explain.
(b) Which is the positive pole, metal X or Y?
(c) (i)
How can a salt bridge be prepared?
(ii) State the main functions of the salt bridge.
[5M]
16
8.
Consider the simple chemical cell shown below.
flow of electrons
aluminium
nickel
nickel(II) salt
solution
porous partition
aluminium salt
solution
(a) What is the function of the porous partition?
(b) Which metal, nickel or aluminium, is more reactive? Explain your answer.
(c) Write ionic half equations for the reactions taking place in each side of the
cell.
(d) Suggest ONE method to increase the voltage of the cell.
[8M]
17
9.
Consider the simple chemical cell shown below.
zinc electrode
silver electrode
bubbles of
hydrogen gas
dilute sulphuric acid
Hydrogen gas is liberated at the silver electrode.
(a) State the direction of electron flow in the external circuit of the cell.
(b) (i)
Is the silver electrode positive pole or negative pole?
(ii) Is the silver electrode anode or cathode?
(iii)
Write an ionic half equation for the reaction taking place at the
silver electrode.
(c) Write an equation for the overall cell reaction.
(d) The milliammeter reading drops after the cell has operated for some time.
(i) Suggest a hypothesis to explain why the current decreases.
(ii) Describe how you would verify your hypothesis.
18
[12M]
10. Consider the simple chemical cell shown below.
A
metal electrode M
iron nail
iron(II) sulphate
solution
X
Y
salt solution of
metal M
(a) In which half-cell is reduction taking place?
(b) Which is the positive electrode of the cell?
(c) What is A and what is its purpose?
(d) Suggest THREE possible metals for M and give the formulae of their
common ions.
[7M]
19
Answers :
Multiple-choice questions :
1
2
3
4
5
6
7
8
9
10
B
D
D
D
A
C
A
D
C
B
11
12
13
14
15
16
17
18
19
20
B
C
A
D
D
B
A
A
D
C
21
22
23
24
25
26
27
28
29
30
B
A
A
A
Conventional questions :
1.
(a) (i) X [1]
(ii) Z [1]
(iii) W [1]
(b) Y is a secondary cell [1] becuase it is rechargeable. [1]
(c) (i) It could be used in portable radios/torches/clocks and calculators.(Any ONE)
[1]
(ii) It could be used in photo flashguns/MP3 players/motorized
toys/shavers/portable TVs. (Any ONE) [1]
(iii) It could be used in quartz watches/calculators/cigarette lighters/hearing aids.
(Any ONE) [1]
2.
(a) From zinc electrode to copper electrode. [1]
(b) Copper electrode. [1]
(c) The reading of the ammeter would increase. [1] It is because 0.2 M sulphuric
acid contains more mobile ions to conduct electricity. [1]
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(d) The reading of the ammeter would decrease. [1] It is because ethanoic acid is a
weak acid which only slightly ionizes in water, [1] providing less mobile ions to
conduct electricity. [1]
3.
(a) From zinc electrode to lead electrode. [1]
(b) Zinc electrode. [1]
(c) Zn(s)  Zn2+(aq) + 2e [1]
(d) The reading of the voltmeter would drop to zero. [1] As sugar is not an
electrolyte, there is no mobile ion to conduct electricity. [1]
4.
(a) From Y to X. [1]
(b) From Y to X. [1]
(c) From Y to X. [1]
5.
(a) Voltmeter, milliammeter, digital multimeter or a data-logger connected to a
computer. [1]
(b) (i) Magnesium/silver [1]
(ii) 0 V [1]
(c) (i) An electrolyte is a compound, which allows electricity to flow through it
only when molten or in aqueous solution. There is chemical decomposition
during the conduction of electricity. [1]
(ii) Yes. [1]
6.
(a) Mg(s)  Mg2+(aq) + 2e [1]
(b) Fe2+(aq) + 2e  Fe(s) [1]
(c) From magnesium electrode to iron electrode. [1]
(d) (i) Magnesium electrode dissolves gradually in the magnesium sulphate
solution. [1]
(ii) A black solid deposit forms on the iron electrode. [1] The colour of the pale
green solution in the half-cell slowly becomes paler slowly. [1]
(e) To complete the circuit by allowing ions to move from one half-cell to another
half-cell, [1] and to balance the charges in the solutions of the two half-cells. [1]
21
(f)
Removing the filter paper would cause a short circuit, [1] thus the voltmeter
reading drops to zero. [1]
7.
(a) Since electrons flow from metal Y to metal X, indicating that metal Y is more
reactive. [1]
(b) Metal X. [1]
(c) (i) It can be prepared by soaking a piece of filter paper in sodium nitrate
solution/sodium chloride solution. [1]
(ii) To complete the circuit by allowing ions to move from one half-cell to
another half-cell. [1]
It provides ions to balance the charges in the solutions of the two half-cells.
[1]
8.
(a) It serves as a salt bridge. [1] It prevents the direct mixing of the two electrolytes,
[1] but allow ions to pass through to complete the circuit. [1]
(b) Aluminium is more reactive, [1] as electrons flow from aluminium to nickel,
indicating that aluminium loses electrons more readily. [1]
(c) Al(s)  Al3+(aq) + 3e [1]
Ni2+(aq) + 2e  Ni(s) [1]
(d) Replace nickel with a less reactive metal such as copper. [1]
9.
(a) From zinc to silver. [1]
(b) (i) Positive. [1]
(ii) Cathode. [1]
(iii) 2H+(aq) + 2e  H2(g) [1]
(c) Zn(s) + 2H+(aq)  Zn2+(aq) + H2(g) [1]
(d) (i) The hydrogen gas bubbles form an insulating layer on the surface of silver,
this causes an increase in the resistance of the cell. The current flowing in
the circuit thus decreases. [2]
(ii) Use a brush to scrape off the gas bubbles covering the surface of silver
electrode. The milliammeter reading should increase immediately. [2]
22
10.
(a) Y [1]
(b) Metal electrode M. [1]
(c) A is a salt bridge. [1] Its function is to complete the circuit by allowing ions to
move from one half-cell into the other. [1]
(d) Lead, Pb2+, copper, Cu2+, silver, Ag+ [3]
23