S.4 Chemistry Supplementary Exercise 2012-2013
Name: _________________________________
Class and class number: S.4 ___ (
Block: _____
Mark:
/ 110
)
Part A: Multiple choice questions
1.
Oxygen can be obtained from the
(1) fractional distillation of liquefied air.
(2) reaction between calcium and water.
(3) electrolysis of dilute sodium chloride solution with graphite electrodes.
A.
2.
3.
4.
B.
(2) only
C.
(1) and (3) only
D.
(2) and (3) only
Lithium has two isotopes, 6Li and 7Li. The relative abundance of 7Li is 92.5%. Which of the following
statements about the two isotopes is INCORRECT?
A.
7
B.
They have the same number of outermost shell electrons.
C.
The relative atomic mass of lithium is 6.93.
D.
They give out flames of different colours in the flame test.
Li has one more neutron than 6Li.
Which of the following statements about bromine and chlorine is correct?
A.
Both of them are coloured gases at room temperature and pressure.
B.
Bromine is more reactive than chlorine.
C.
Both of them are poisonous.
D.
Both of them react with sodium to form simple molecular substances.
Metal X forms a phosphate with the formula X3(PO3)2. What is the chemical formula of its
hydrogencarbonate?
A.
5.
(1) only
XHCO3
B.
X(HCO3)2
C.
X3(HCO3)2
D.
X(HCO3)3
Which of the following combinations about the atomic structure of 26Mg2+ is correct?
Number of protons
Number of neutrons
Number of electrons
A.
13
12
11
B.
13
12
15
C.
12
13
10
D.
12
14
10
6.
In which of the following tubes will the iron nail rust after a few days?
(1)
A.
7.
8.
(2)
(3)
iron nail
air
iron nail
air
iron nail
0.1 M sodium
hydroxide
solution
0.1 M calcium
chloride solution
0.1 M sodium
hydroxide
solution
(1) and (2) only
B.
(1) and (3) only
C.
(2) and (3) only
D.
(1), (2) and (3)
Which of the following samples contains the largest number of atoms?
A.
5.0 g of carbon dioxide
B.
5.0 g of steam
C.
5.0 g of nitrogen
D.
5.0 g of sulphur trioxide
Which of the following hazard warning labels should be displayed on a bottle of concentrated sulphuric
acid?
A.
and
B.
and
C.
and
D.
and
9.
A mixture of copper(II) sulphate and copper(II) bromide contains 0.3 mole of sulphate ions and 0.6 mole
of bromide ions. How many moles of copper(II) ions are in the mixture?
A. 0.6 mol
B. 0.8 mol
C. 0.9 mol
D. 1.1 mol
10. In the Ostwald Process, the following reaction occurs:
4NH3(g) + 5O2(g)  4NO(g) + 6H2O(l)
Which of the following statements about ammonia is/are correct?
(1)
It is the reducing agent.
(2)
The oxidation number of nitrogen in ammonia decreases.
(3)
It loses electron(s).
A.
(1) only
B.
(2) only
C.
(1) and (3) only
D.
(2) and (3) only
11. The following diagram shows a simple chemical cell.
salt bridge
graphite electrode
graphite electrode
silver sulphite solution
acidified potassium
permanganate solution
Which of the following statements concerning the above chemical cell are INCORRECT?
(1) Electrons flow from the right electrode to the left electrode in the external circuit.
(2) Potassium chloride solution can be used as an electrolyte in the salt bridge.
(3) The colour of acidified potassium permanganate solution changes from purple to colourless.
A.
(1) and (2) only
B.
(1) and (3) only
C.
(2) and (3) only
D.
(1), (2) and (3)
12. Which of the following statements concerning the electrolysis of copper(II) sulphate solution using
graphite electrodes are correct?
(1)
The pH value of the solution gradually decreases.
(2)
Copper is deposited at the cathode.
(3)
Hydrogen gas is given off at the anode.
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
13. Which of the following compounds when heated can produce a gas that relights a glowing splint?
A. Copper(II) oxide
B. Silver oxide
C. Calcium oxide
D. Iron(III) oxide
14. An element forms a compound X2Cl3 which contains 25% by mass of chlorine. What is the relative atomic
mass of the element X?
(Relative atomic mass: Cl = 35.5)
A.
39.9
B.
79.9
C.
106.5
D.
159.8
15. Which of the following statements concerning the electrolysis of concentrated sodium bromide solution
using graphite electrodes are correct?
(1) The main product at the anode is O2(g).
(2) H+(aq) ions are preferentially discharged at the cathode to form H2(g).
(3) The solution becomes sodium hydroxide solution after electrolysis.
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
16. Which of the following is the correct order of melting point of Na2O, SiO2 and SO2?
A. Na2O < SiO2 < SO2
B. SO2 < Na2O < SiO2
C. SiO2 < Na2O < SO2
D. SO2 < SiO2 < Na2O
17. 5.20 g of a dibasic acid H2X dissolves completely in distilled water and is then diluted to 250.0 cm3. 25.0
cm3 of the diluted solution requires 20.0 cm3 of 0.50 M sodium hydroxide solution for complete
neutralization. What is the molar mass of the acid?
A. 52.0 g mol1
B. 104.0 g mol1
C. 260.0 g mol1
D. 520.0 g mol1
18. Consider the following chemical equation:
2MnO4(aq) + xH2O2(aq) + yH+(aq)  2Mn2+(aq) + xO2(g) + zH2O(l)
Which of the following combinations is correct?
x
y
z
A.
1
8
4
B.
1
8
8
C.
5
10
4
D.
5
6
8
19. In which of the following atoms or ions is the outermost shell an octet?
(1) Li+
(2) Ar
(3) P3–
A. (1) only
B. (2) only
C. (1) and (3) only
D. (2) and (3) only
20.
X, Y and Z are metals. The table below shows the observations when each of them is put into copper(II)
sulphate solution:
Metal
Observation
X
no observable change
Y
brown solid formed and colourless gas evolved
Z
brown solid formed
Which of the following arrangements correctly represents the ascending order of reactivity of the metals?
A. X < Z < Y
B. Y < Z < X
C. Z < X < Y
D. X < Y < Z
21. The oxide of metal Z reacts with dilute hydrochloric acid to form a colourless solution. Which of the
following metals may Z be?
(1) zinc
(2) copper
A. (1) only
(3) silver
B. (2) only
C. (1) and (3) only
D. (2) and (3) only
22. Which of the following pairs of ions would react together to form a white precipitate?
A. Ca2+(aq) and SO42– (aq)
B. Ni2+(aq) and NO3– (aq)
C. Cu2+(aq) and OH–(aq)
D. NH4+(aq) and OH–(aq)
23. Oxalic acid is a dibasic acid. 10.0 cm3 of an aqueous solution of oxalic acid requires 30.0 cm3 of 0.1 0 M
KOH(aq) for complete neutralisation. What is the concentration of the oxalic acid solution?
A. 0.15 M
B. 0.20 M
C. 0.30 M
D. 0.60 M
24. X is an acid. 25.0 cm3 of 0.20 M solution X requires 30.0 cm3 of 0.50 M sodium hydroxide solution for
complete neutralisation. What is the basicity of X?
A. 1
B. 2
C. 3
D. 4
25. Which of the following substances can decolourise acidified potassium permanganate solution?
(1) sodium nitrate solution
A. (1) only
(2) sodium sulphite solution
B. (2) only
(3) chlorine water
C. (1) and (3) only
D. (2) and (3) only
26. The following diagram shows the set-up of a chemical cell.
Given that Br2(aq) is a stronger oxidising agent than Fe3+(aq), which of the changes represented by the
following half equations would occur if the cell is producing a current?
(1) Fe3+(aq) + e– → Fe2+(aq)
(2) Fe2+(aq) → Fe3+(aq) + e–
(3) 2 Br–(aq) → Br2(aq) + 2 e–
A. (1) only
27.
B. (2) only
C. (1) and (3) only
D. (2) and (3) only
In an experiment of electroplating nickel on a copper object, which of the following combinations is
correct?
Anode
Cathode
Electrolyte
A. copper object
nickel
CuSO4(aq)
B. copper object
nickel
NiSO4(aq)
C. nickel
copper object
CuSO4(aq)
D. nickel
copper object
NiSO4(aq)
28. A sample of zinc granules of mass 1.8 g was added to 100 cm3 of 0.25 M hydrochloric acid. What is the
theoretical volume of hydrogen produced at room temperature and pressure?
(Relative atomic mass: Zn = 65.4; molar volume of gas at room temperature and pressure = 24 dm3)
A. 0.30 dm3
B. 0.33 dm3
C. 0.60 dm3
D. 0.66 dm3
29. Methane (CH4) burns completely in oxygen according to the following equation:
CH4 + 2O2 → CO2 + 2H2O
What is the mass of oxygen required for the complete combustion of 48 g of methane?
(Relative atomic masses: H = 1.0, C = 12.0, O = 16.0)
A. 48 g
B. 96 g
C. 192 g
D. 384 g
30. In which of the following compounds does sulphur exhibit the lowest oxidation number?
A. Na2S2O3
B. MgSO4
C. KHSO3
D. H2S2O7
31. Which of the following statements concerning the reaction between carbon and concentrated sulphuric acid
are correct?
(1) The oxidation number of carbon changes from 0 to +4.
(2) The oxidation number of hydrogen in sulphuric acid remains unchanged.
(3) Concentrated sulphuric acid acts both as a dehydrating agent and an oxidising agent.
A. (1) and (2) only
Directions:
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
Each question below (Questions 32 to 33) 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.
1st statement
2nd statement
32. Graphite is a good conductor of
electricity.
In graphite, layers of carbon atoms are
held together by weak van der Waals’
forces.
33. Ethanoic acid is a weak acid.
Ethanoic acid ionizes slightly in water to
form hydrogen ions.
Part B: Structured questions
1.
For each of the three substances below, write down the condition(s) for conducting electricity and
the corresponding explanation(s). The first one has been done for you.
(7 marks)
Substance
Condition(s) for
conducting electricity
(a) Diamond
It cannot conduct
electricity at any physical
state.
Explanation(s) for conducting electricity or not
conducting electricity
(b) Sodium
(c) Sodium
chloride
2.
Food deteriorates in the presence of oxygen in air. However, some packaged foods can be stored for
several months to years because a small packet of oxygen absorber is added to the food container. The
packet consists mainly of iron powder. The principle of oxygen absorber is that iron powder inside the
packet reacts with oxygen and moisture in the air to form hydrated iron(III) oxide, Fe2O3˙nH2O.
(a)
Write a chemical equation for the reaction in the oxygen absorber.
2.
(b)
The packaging material of oxygen absorber for food is usually made of paper. Explain whether
a thin sheet of plastic can be used as the packaging material for the oxygen absorber.
(c)
Your teacher asked you to judge whether the small packet of oxygen absorber is a brand new one
or a used one. Suggest how you can accomplish the task.
(d)
(i)
Explain why iron powder, instead of a piece of iron with the same mass, is put into the
packet of oxygen absorber.
(ii)
It was found that a small amount of sodium chloride solid was present in the packet of
oxygen absorber. Suggest ONE reason for this.
(8 marks)
3.
For each of the following pairs of compounds, suggest a chemical test to distinguish between them. In
your answers, you should include:
(1)
appropriate reagents and conditions (if necessary);
(2)
observations for both compounds; and
(3)
all chemical equation(s) involved. (Ionic equations will NOT be accepted.)
(a)
Copper(II) oxide and iron(III) oxide.
(b)
Ammonium chloride solution and sodium chloride solution.
(7 marks)
4.
Account for the following phenomenon.
(i)
Scratching on a food can speeds up rusting.
(ii) Fizzy tablets should be stored in dry places.
(5 marks)
4.
(b) Neon has two isotopes, 20Ne and 22Ne. The relative atomic mass of neon is 20.2.
(i)
Calculate the relative abundance of each isotope.
(ii)
Calculate the number of 22Ne atoms present in 10.48 g of neon.
\
(Avogadro constant L = 6.02 × 1023 mol–1)
(4 marks)
5.
Describe how you could make a dry sample of magnesium chloride crystals from magnesium carbonate
and dilute hydrochloric acid.
(9 marks)
6.
In a titration analysis, a standard hydrochloric acid was used to determine the percentage purity of a sample
of calcium oxide.
(a) What is meant by the term ‘standard solution’?
(1 mark)
(b) A student prepared the standard hydrochloric acid by diluting a concentrated hydrochloric acid of
known concentration.
(i)
Describe briefly the procedure for the dilution.
(ii) It was found that the concentration of the solution prepared in (i) is less than expected. Explain
briefly.
(iii) Suggest a method to determine the concentration of hydrochloric acid prepared in (i).
(5 marks)
6.
(c)
The concentration of the standard hydrochloric acid was determined to be 1.23 M. 1.78 g of
an impure sample of calcium oxide required 28.40 cm3 of 1.23 M hydrochloric acid for complete
neutralization. Calculate the percentage purity of calcium oxide sample.
(Assume that the impurities in the sample do not react with hydrochloric acid.)
7.
(3 marks)
A student performed an experiment of fermentation by mixing 10.0 g of glucose (C6H12O6), 25.0 cm3 of
distilled water and 1 spatula of yeast (a biological catalyst) in a conical flask. A colourless gas G was
evolved after mixing. The volume of the gas G evolved was measured after the fermentation. The chemical
equation for the fermentation is shown below.
yeast
C6H12O6(aq)  2CH3CH2OH(aq) + 2G(g)
(a) What is the gas G?
________________________________________.
(1 mark)
(b) At room temperature and pressure, the volume of gas G collected was 267 cm3. Calculate the
percentage yield of gas G in the reaction.
(At room temperature and pressure, molar volume of a gas = 24.0 dm3 mol1, density of water = 1 g
cm3)
(3 marks)
7.
8.
(c) Suggest ONE reason why percentage yield of ethanol in this reaction is quite low.
(1 mark)
When excess sodium sulphite solution is mixed with an aqueous solution of bromine, the yellow/brown
bromine water is decolorized. Write
(a) the oxidation half equation.
(b) the reduction half equation.
(c) the overall ionic equation.
(d) the reason for the colour change.
(4 marks)
9.
A student added 46.0 g of sodium to 48.0 g of water and observed what happened.
(a) Write a chemical equation of the reaction involved.
(b) Determine which reactant is in excess.
(11 marks)
9.
(c) Calculate the mass of hydrogen that could be obtained.
(d) State how sodium could be stored in school laboratories.
10. The following set-up shows the electrolysis of dilute silver sulphate solution using graphite electrodes.
graphite electrode X
graphite electrode Y
silver sulphate solution
(a) (i)
Write an ionic equation for the reaction occurring at electrode X.
(ii) State the product formed at electrode X. Explain your answer.
(b) (i)
Write an ionic equation for the reaction occurring at electrode Y.
(ii) State the product formed at electrode Y. Explain your answer.
(8 marks)
-End-