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Chemistry
WAEC / WASSCE 2010
Oxidation, Reduction & Redox Reactions
What is the change in oxidation number of manganes in the reaction represented by the following equation? MnO-4(aq) + 8H+(aq) + 5e- → Mn2+(aq) + 4H2O(l)
A
+3 to + 2
B
+ 4 to + 2
C
+ 5 to + 2
D
+ 7 to 2
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #37529)
Chemistry
WAEC / WASSCE 2010
Electrolysis & Electrochemical Cells
The quantity of electricity required to discharge 1 mole of univalent ion is
A
9,600 C
B
48,250 C
C
96,500 C
D
193,00 C
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37533)
Chemistry
WAEC / WASSCE 2010
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Fact and oils are used as raw materials in the following industries except
A
paint industry
B
plastic industry
C
margarine industry
D
cosmetics industry
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #37534)
Chemistry
WAEC / WASSCE 2010
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Solution
An advantage of detergent over soap is that detergents
A
are readily available
B
are in powerdered from
C
are non-biodegradable
D
lather readily with water
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Detergent lather readily with water. Soap does not lather readily with water. Soap is a good cleansing agent in soft water, in hard water it forms scum.
Source: Myschool Past Questions Archive (Record #37538)
Chemistry
WAEC / WASSCE 2010
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
The products of fermentation of sugar are
A
carbon(IV) oxide and water
B
ethanol and carbon (IV) oxide
C
ethanol and water
D
ethanol and enzymes
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #37539)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
The IUPAC name of C2H6COOC2,/sub>H6 is
A
ethyethanoate
B
ethylproanoate
C
propylethanoate
D
propylpropanoate
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #37540)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
An organic compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. What is the empirical formula of the compound? [O = 16.0, C = 12.0, H = 1.0]
A
C2HO
B
CHO
C
CH2O
D
CHO2
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37544)
Chemistry
WAEC / WASSCE 2010
Organic Chemistry II: Functional Groups, Polymers & Biomolecules
Compound N reacts with sodium metal to produce a gas that gives a 'pop' sound with a burning splint N also react with ethanoic acid to give a sweet smelling liquid. Compound N is an
A
alkanol
B
alkanoate
C
alkane
D
alkanoic acid
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37545)
Chemistry
WAEC / WASSCE 2010
Metals, Transition Elements & Extraction
The main function of limestone in the blast furnance is to
A
act as a reducing agent
B
act as a catalyst
C
remove impurities
D
supply carbon (IV) oxide
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37548)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following substances cannot be classified as a heavy chemical?
A
AgNO3
B
CaO
C
CaOCI2
D
H2SO4
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37549)
Chemistry
WAEC / WASSCE 2010
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following metals exists as liquid at ordinary temperature?
A
Copper
B
Gold
C
Mercury
D
Silver
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37550)
Chemistry
WAEC / WASSCE 2010
Non-Metals & Their Compounds
Solution
(a) Name one product of destructive distillation of coal that is (i) solid (ii) liquid; (iii) gas.
(b) (i) What is the major component of synthetic gas? (ii) Give one reason why synthetic gas is not a major source of air pollution.
(c) (i) Write a balanced chemical equation for the complete combustion of carbon. (ii) State two: I. physical; II. chemical properties of the product in (c)(i).
(d) (i) Name two allotropes of carbon that are I. crystalline, II. amorphous. (ii) State one use of each of the allotropes named in (d)(i).
(e) (i) By means of balanced chemical equations only, outline the process of manufacture of H\(_2\)SO\(_4\), by contact process.
(ii) State the function of H\(_2\)SO\(_4\) in each of the following reaction equations:
I. C\(_2\)H\(_5\)OH\(_{2(l)}\) \(\to\) C\(_2\)H\(_{4(g)}\);
II. Pb(NO\(_{3(g)}\) + H\(_2\)SO\(_{4(g)}\) —> PbSO\(_{4(s)}\) + 2HNO\(_{3(aq)}\)
A
Copper
B
Gold
C
Mercury
D
Silver
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
(a)(i) coke (ii) ammoniacal liquor/coal tar (iii) coal gas
(b) (i) methane (ii) because sulphur is removed in the gasification process/it does not contain sulphur or sulphur compounds.
(c)(i) C\(_{(S)}\) + O\(_{2(g)}\) --> CO\(_{2(g)}\)
(ii) I. is a gas at room temperature - it is a colourless gas - it is an odourless gas - it is denser than air - it readily liquefies and solidifies/easily compressible.
II. - reacts with alkali to form trioxocarbonate (IV) - it is soluble in water - reacts with (burning) Mg to form MgO - reacts with red hot carbon to form CO - It is weakly acidic in water - it does not support combustion.
(d)(i) I. diamond graphite II. -coal/ lampblack/soot/carbon black - coke - charcoal.
(ii) I. Diamond - as a cutting tool - as jewellery;
Graphite - as a lubricant - as an electrode - as pigment in paints - as neutron moderators in nuclear reactors.
II. Coke - as a fuel -as a reducing agent/in the extraction of metals - preparation of carbides - for making water gas/producer gas.
Coal - as a fuel -as a starting material for chemicals.
Charcoal - as a fuel - as absorbent/in gas mask - in the purification of gases - in the recovery of industrial solvent - for removing colouring matter from substances
Lampblack/Soot/carbon black: - to colour rubber tyres - to make boot/shoe polish - to make printers ink - to make black paint - typewriting ribbons - carbon paper.
(e)(i) I. S\(_{(s)}\) + O\(_{2(g)}\) --> SO\(_{2(g)}\)
II. 2SO\(_{2(g)}\) + O\(_{2(g)}\) \(\rightleftharpoons\) 2SO\(_{3(g)}\)
III. SO\(_{3(g)}\) + H\(_2\)SO\(_{4(g)}\) -> H\(_2\)S\(_2\)O7\(_{7(l)}\)
IV. H\(_2\)SO7\(_{7(l)}\) + H\(_2\)O\(_{(l)}\) -> 2H\(_2\)SO\(_{4(l)}\)
(ii) I. - dehydrating agent
II. precipitating agent/displacement agent.
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 2010
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
(a) i) Give the name and nature of the radiations that are emitted during radioactivity.
ii) State two differences between chemical reaction and nuclear reaction.
iii) Balance the following nuclear reactions and identify X and Y.
I. \(^{212}_{84} PO\) \(\to\) \(^{208}_{82} Pb\) + X
II \(^{137}_{55}Cs\) \(\to\) \(^{137}_{55}Ba\) + Y
(b) The electron configuration of an element X is: 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^5\)
(i) Deduce the atomic number of X.
(ii) To what group does X belong?
(iii) Give two properties of the group to which the element X belong.
(iv) Identify element X by name.
(v) Write a balanced equation to represent the reaction between the element X and hot concentrated NaOH.
(c)(i) Explain why: I. graphite is used as a lubricant; II. diamond is used as an industrial cutting tool.
(ii) Write an equation to represent the reaction between aqueous HCI and NH\(_3\) solution.
(iii) Name the type of reaction represented by the equation.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i)- alpha particle, (doubly charged) helium nucleus/high ionizing/low penetrating power/deflected towards negative plate.
- beta particle, (fast moving) electron/moderate ionizing/moderate penetrating power/deflected towards positive plate.
- gamma radiation, (high energy) electromagnetic radiation/low ionizing/high penetrating power effect in magnetic field.
(ii)
Chemical Reaction
Nuclear Reaction
- atoms are rearranged by the breaking and forming of chemicarbondlno new atom is formed/atomic number or mass number of each element does not change.
- only (valence) electrons are involved.
- reactions are accompanied by absorption /release of (relatively) small amount of energy.
- rate of reaction is influenced by temperature, pressure, concentration and catalyst.
- elements are converted to other elements/new elements may be formed/atomic number or mass number of each element may change
- protons, neutrons, electrons and other elementary particles may be involved.
- reactions are accompanied by release of (relatively) large amount of energy.
- rate of reaction normally is not affected by pressure, temperature and catalyst.
(iii) I. \(^{212}_{84}Po\) \(to\) \(^{208}_{82}Pb\) + \(^{4}_2X\) (X is \(\alpha\)-particle/helium nucleus/\(^{4}_2He\))
II. \(^{137}_{55}Cs\) \(\to\) \(^{137}_{56}Ba\) + \(^{0}_{-1}Y\) (Y is \(\beta\)-particle/electron/ \(^{0}_{-1}He\))
(b).(i) atomic number = 17
(ii) group 7
(iii) - formation of diatomic molecules. - formation of monovalent ions/same valence electrons, - they are coloured substances. - they are oxidizing agents., - most electronegative in its period/smallest atomic size in its period. - they are non-metals.
(iv) chlorine .
(v) 3Cl\(_2\) +6NaOH ----> 5NaCl + NaCIO\(_3\) + 3H\(_2\)O.
(c)(i) I. Graphite consists of planar layers (in which all carbon-carbon bonds extend in two dimensions) which can slide over each other. Hence it is used as lubricant.
II. Diamond consist of (large) three dimensinoal network of carbon-carbon bonds which Makes it hard hence, used as a cutting tool.
(ii) HCI\(_{aq}\) + NH\(_{3(aq)}\) --> NH\(_4\)CI\(_{(aq)}\)
OR HCI\(_{aq}\) + NH\(_4\)HO\(_{aq}\) --> NH\(_4\)Cl\(_{aq}\) + H\(_2\)\(O_l\)
(iii) Combination OR Neutralisation.
Source: Myschool Past Questions Archive (Record #51898)
Chemistry
WAEC / WASSCE 2010
Chemical Bonding & Intermolecular Forces
Solution
(a) (i) Define saturated solution.
(ii) Tha solubility of KNO\(_3\) at 20^\circC was 3.00 mol dm\(^{-3}\) If 67.0g of KNO\(_3\) was added to 250 cm\(^{-3}\) of water and stirred at 20^\circC, determine whether the solution formed was saturated or not at that temperature. [ KNO\(_3\) = 101.0 ]
(b) (i) Distinguish between dative bond and covalent bond.
(ii) Explain why sugar and common salt do not conduct electricity in the solid state.
(iii) State the type of intermolecular forces present in: I. hydrogen fluoride; II argon.
(iv) Consider the compounds with the following structures. S - H ---- N and O - H ---- N In which of the compounds is the hydrogen bend stronger? Give reason for your answer.
(c) (i) State Dalton's Law of Partial Pressure.
(ii) If 200cm of carbon (IV) oxide were collected over water at 18^\circC and 700 mmHg, determine the volume of the dry gas at s.t.p. [ standard vapour pressure of water at 18^\circC = 15 mmHg]
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) A saturated solution is that which contains the maximum amount of solute it can dissolve at a given temperature (in the presence of undissolved solute).
(ii) solubility of KNO\(_3\) in gdm\(^{-3}\) = 3.00 x 101. = 303
1000cm\(^{3}\) of saturated solution ---- 303g
250cm\(^{3}\) of the solution = \(\frac{303 \times 250}{1000}\) = 75.8 g.
Since the quantity of KNO\(_3\) added (67.0) to 250 cm\(^{3}\) of water is less than maximum amount required to form a saturated solution, then the solution is unsaturated.
(b)(i) In dative bond, only one of the participating atoms/species donates the electrons to be shared by both atoms while in covalent bond both participating atoms/species contribute equally the electrons being shared.
(ii) Sugar is covalent while common salt (NaCI) is electrovalent/ionic. Electrical conductivity (in compounds) depends on presence of mobile ions. Sugar does not conduct electricity because it does not contain ions (they are molecules) while solid common salt does not conduct electricity because its ions are not mobile.
(iii) I. Hydrogen bond.
(iv) H. Van der Waals forces.
(iv) O - H --- N Because oxygen is more electronegative and smaller in size than sulphur.
(c)(i) The total pressure exerted by a mixture of gases which do not-react chemically is equal to the sum of the individual partial pressures of the gases in the mixture.
(ii) pressure of the dry gas (P\(_1\) = 700 - 15 = 685 mmHg, V\(_1\) = 200 cm\(^3\), T\(_1\) = 18^\circC = 273 + 18 = 291K, P\(_2\) = 760 mmHg, T\(_2\) = 273
\(\frac{P_1V_1}{T_1}\) =\(\frac{P_2V_2}{T_2}\)
V\(_2\) = \(\frac{P_1V_1T_2}{P_2T_1}\)
\(\frac{685 \times 200 \times 273}{760 \times 291}\)
= 169.1 cm\(^{3}\)
Source: Myschool Past Questions Archive (Record #51901)
Chemistry
WAEC / WASSCE 2010
Electrolysis & Electrochemical Cells
Solution
(a) (i) Define a base according to Arrhenius concept.
(ii) Give one example of an Arrhenius base.
(iii) Identify each of the following substances in aqueous solutions as strong electrolyte, non-electrolyte or weak electrolyte.
I. C\(_{12}\)H\(_{22}\)O\(_{11}\) II. NH\(_3\) Ill. NaOH
(iv) Write a balanced equation to represent the reaction between CH\(_3\)COOH and KOH.
(b) Calculate the volume of 0.500 mol dm\(^{-3}\) HCI required to neutralize 20.00 cm\(^3\) of 0.300 mol dm\(^{-3}\) NaOH.
(c) Give the IUPAC name of each of the following salts: (ii) NaOCI; (iii) Mg(HCO\(_3\))\(_2\).
(d)(i) Define the term standard solution.
(ii) Consider the following compounds: NaOH and Na\(_2\)CO\(_3\). Which of the compounds is suitable for the preparation of a standard alkaline solution? Give reason for your answer
(iii) Fe completely reacted with dilute HCI.
I. Write an equation for the reaction
II. If 3.08g of Fe completely reacted with 50.0 cm\(^3\) of 2.20 mol dm\(^{-3}\) HCI, calculate the relative atomic mass of the metal.
medium Difficulty
Verified Correct Answer: Option
Chemical Principles & Mechanism
(a)(i) A base is a substance which produces hydroxyl (OH\(^-\)) ions in its aqueous solution.
(ii) NaOH/Ca(OH)\(_2\)/ KOH.
(iii) I. non-electrolyte II. weak electrolyte HI. strong electrolyte.
(iv) CH\(_3\)COOH + KOH --> CH\(_3\)COOK + H\(_2\)O
(b) \(\frac{C_AV_A}{C_BV_B}\) = 1
V\(_A\) = \(\frac{C_BV_B}{C_A}\)
\(\frac{0.30 \times 20.50}{0.50}\) cm\(^3\)
(c)(i) sodium oxochiorate 1 (ii) magnesium (iii) hydrogen trioxocarbonate(IV).
(d)(i) A standard solution is a solution whose concentration is (accurately) known.
(ii) Na\(_2\)CO\(_3\); Na\(_2\)CO\(_3\) is easy to weigh accurately because it is stable in air/non-deliquescent.
(iii) I. Fe\(_{(s)}\) + 2HCl\(_{(aq)}\) \(\to\) FeCl\(_{2(aq)}\) + H\(_{2(aq)}\).
II. number of moles of HCI used = 2.20 x \(\frac{50.0}{1000}\) = 0.11
mole ratio of HCI : Fe = 2 : 1
number of moles of Fe used = \(\frac{0.11}{2}\) = 0.055 mole
0.055 mole of Fe = 3.08g
0.1 mole of Fe = \(\frac{3.08 \times 1.0}{0.055}\) = 56g
Relative atomic mass of Fe = 56.
Source: Myschool Past Questions Archive (Record #51903)