2018 Chemistry WAEC SSCE (School Candidates) May/June

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Chemistry 1 - Objective Test Questions

Which of the following raw materials is used in the plastic industry?
1. Ethene.
2. Methane.
3. Sulphur.
4. Hydrogen.
Which of the following organic compounds can undergo both addition and substitution reactions?
1. Petane.
2. Benzene.
3. Propane.
4. Hexane.
Which of the following equations represents a redox reaction?
1. ${\ce {AgNO3{}_{(aq)}+ KCl{}_{(aq)}-> AgCl{}_{(s)}+ KNO3{}_{(aq)}}}$
2. ${\ce {HNO3{}_{(aq)}+ NaNO{}_{(aq)}-> NaNO3{}_{(aq)}+ H20{}_{(l)}}}$
3. ${\ce {CaCO3{}_{(s)}-> CaO{}_{(s)}+ CO3{}_{(aq)}}}$
4. ${\ce {2H2S{}_{(s)}+ SO2{}_{(g)}-> 2HO2{}_{(s)}+ 3S{}_{(g)}}}$
The process of extraction of iron from its ore is
1. decomposition.
2. oxidation.
3. reduction.
4. sublimation.
What is the solubility of a salt if 0.4g of it is obtained on evaporating 200 $cm^{3}$ $cm^{3}$ of its saturated solution to dryness?
1. 0.08 $gdm^{-3}$
2. 2.00 $gdm^{-3}$
3. 8.00 $gdm^{-3}$
4. 80.00 $gdm^{-3}$
An acidic salt has
1. Double anions in its aqueous solution.
2. A single cation in its aqueous solution.
3. Hydrogen ions in its aqueous solution.
4. Hydrogen atoms in its aqueous solution.
A reaction is endothermic if the
1. Reaction vessel feels cool during the reaction.
2. Enthalpy change is negative.
3. Bond forming energy exceeds bond breaking energy.
4. Heat of formation of reactants exceeds heat of formation of products.
In which of the following compounds does hydrogen form ionic compounds?
1. ${\textstyle {\ce {CH4}}}$
2. HCl
3. ${\textstyle {\ce {NH3}}}$
4. NaH
Consider the following reaction equation: ${\ce {Br2 + 2KL -> 2KBr + L2}}$ ${\ce {Br2 + 2KL -> 2KBr + L2}}$ . Bromine is acting as
1. An oxidizing agent
2. A reducing agent
3. An acid
4. A base
An organic compound has the empirical formula ${\textstyle {\ce {CH2}}}$ ${\textstyle {\ce {CH2}}}$ . if the molar mass is 42 $gmol^{-1}$ $gmol^{-1}$ , what is the molar formula? [H=1.0, C=12.0]
1. ${\textstyle {\ce {C2H4}}}$
2. ${\textstyle {\ce {C3H4}}}$
3. ${\textstyle {\ce {C3H6}}}$
4. ${\textstyle {\ce {C4H8}}}$
Ethene is produced from ethanol by
1. Decomposition
2. Hydrolysis
3. Ozonolysis
4. Dehydration
Consider the following equilibrium reaction: ${\ce {2AB2{}_{(g)}+ B2{}_{(g)}<=> 2AB3{}_{(g)}}}$ ${\ce {2AB2{}_{(g)}+ B2{}_{(g)}<=> 2AB3{}_{(g)}}}$ $\bigtriangleup$ $\bigtriangleup$ H= -X $kJmol^{-1}$ $kJmol^{-1}$ . The backward reaction will be favored by
1. A decrease in pressure.
2. An increase in pressure.
3. A decrease in temperature.
4. An introduction of a positive catalyst.
What is the mass of solute in 500 $cm^{3}$ $cm^{3}$ cm? of 0.005 $moldm^{-3}$ $moldm^{-3}$ ${\ce {H2SO4}}$ ${\ce {H2SO4}}$ ? [H=1.0. O=16.0. S=32.0]
1. 0.490g
2. 0.0492g
3. 0.245g
4. 0.0245g
Pure water can be made to boil at a temperature lower than 100°C by
1. Reducing its quantity.
2. Decreasing the external pressure.
3. Distilling it.
4. Increasing the external pressure.
Consider the following sketch of the solubility curve of some substances. At what temperature does the solubility of ${\ce {KNO3}}$ ${\ce {KNO3}}$ equal that of ${\ce {NaNO3}}$ ${\ce {NaNO3}}$ ?
1. $0^{\circ }$ C
2. $20^{\circ }$ C
3. $30^{\circ }$ C
4. $40^{\circ }$ C
When a salt is added to its saturated solution, the salt
1. Dissolves and the solution becomes super saturated.
2. Dissolves and the solution becomes unsaturated.
3. Precipitates and the solution remains unchanged.
4. Dissolves and crystals are formed.
When substance X was added to a solution of bromine water, the solution became colorless. X is likely to be
1. Propane.
2. Propanoic acid.
3. Propyne.
4. Propanol.
The preferential discharge of ions during electrolysis is influenced by the
1. Mechanism of electrolysis.
2. Electrolytic reactions.
3. Nature of the electrode.
4. Type of electrolytic cell.
The valence electrons of ${\ce {_12Mg}}$ ${\ce {_12Mg}}$ are in the
1. 3s orbital.
2. 2p orbital.
3. 2s orbital.
4. 1s orbital.
Stainless steel is an alloy compromising of
1. Fe and C.
2. Fe and Ni.
3. Fe, C and Ni.
4. Fe, C and Al
The number of hydrogen ions in 1.0 $dm^{3}$ $dm^{3}$ of 0.02 $moldm^{-3}$ $moldm^{-3}$ tetraoxosulphate(IV) acid is [ ${\textstyle N_{A}}$ ${\textstyle N_{A}}$ = 6.02 x $10^{23}$ $10^{23}$ ]
1. 1.2 x $10^{22}$
2. 1.2 x $10^{23}$
3. 2.4 x $10^{22}$
4. 2.4 x $10^{23}$
The most suitable substance for putting out petrol fire is
1. Water.
2. Carbon(IV)oxide.
3. Fire blanket.
4. Sand.
The following factors would contribute to environmental pollution except
1. Production of ammonia.
2. Manufacture of cement.
3. Photosynthesis.
4. Combustion.
The position of equilibrium in a reversible reaction is affected by
1. Particle size of the reactants
2. Vigorous stirring of the reaction mixture.
3. Presence of a catalyst.
4. Change in concentration of the reactants.
The diagram below illustrate a conical flask containing water and ice. Which of the following statements about the diagram is correct?
1. The water is at a lower temperature than the ice.
2. Energy is absorbed when the ice changes to water.
3. Energy is released when the ice changed to water.
4. The water molecules vibrate about a fixed point.
Which of the following statements best explains the differences between a gases and a vapor?
1. Unlike gases, vapors are liquids at room temperature.
2. Unlike gases, vapor can easily be condensed into liquids.
3. Unlike gases, vapor is readily converted into solids.
4. Vapors are generally denser than gases.
What is the volume of 0.1 $moldm^{-3}$ $moldm^{-3}$ HCl that would completely neutralize 25 $cm^{3}$ $cm^{3}$ of 0.3 $moldm^{-3}$ $moldm^{-3}$ ${\textstyle {\ce {Ca(OH)2}}}$ ${\textstyle {\ce {Ca(OH)2}}}$ ?
1. 150 $cm^{3}$
2. 75 $cm^{3}$
3. 30 $cm^{3}$
4. 25 $cm^{3}$
Cu and ${\textstyle {\ce {HNO3}}}$ ${\textstyle {\ce {HNO3}}}$ are not suitable for preparing hydrogen gas because of their
1. Reactivity and oxidation respectively.
2. Conductivity and corrosiveness respectively.
3. Melting point and reduction respectively.
4. Electronegativity and solubility respectively.
Which of the following formulae cannot be an empirical formula?
1. ${\textstyle {\ce {CH}}}$
2. ${\textstyle {\ce {CH2}}}$
3. ${\textstyle {\ce {P2O5}}}$
4. ${\textstyle {\ce {N2O4}}}$
One of the criteria for confirming the purity of benzene is to determine its
1. Heat capacity.
2. Boiling point.
3. Mass.
4. Color.
When chlorine is passed through a sample of water the pH of the water sample would be
1. <7
2. >7
3. =7
4. 0
How many atoms are contained in 0.2 moles of nitrogen? [N= 6.02 x $10^{23}$ $10^{23}$ ]
1. 1.20 x $10^{23}$
2. 2.41 x $10^{23}$
3. 3.62 x $10^{23}$
4. 4.82 x $10^{23}$
1. Option a
2. Option b
3. Option c
4. Option d
The strength of metallic bonds depends on the
1. Charge density of the atoms.
2. Ductility of the metal.
3. Number of valence electrons.
4. Total number of electrons in the atom.
When zinc is added to ${\textstyle {\ce {AgNO3}}}$ ${\textstyle {\ce {AgNO3}}}$ solution, crystals of silver forms on the zinc surface. This indicates that zinc is
1. Oxidized.
2. Reduced.
3. Decomposed.
4. Dissociated.
The empirical formula of a compound containing 0.067mol Cu and 0.066mol O is [Cu=63.5, O=16.0]
1. ${\textstyle {\ce {Cu2O}}}$
2. ${\textstyle {\ce {CuO}}}$
3. ${\textstyle {\ce {CuO2}}}$
4. ${\textstyle {\ce {Cu2O2}}}$
The change in the oxidation state of iron in the reaction represented by the equation below is ${\textstyle {\ce {2FeCl3 + H2S -> 2FeCl2 + 2HCl + S}}}$ ${\textstyle {\ce {2FeCl3 + H2S -> 2FeCl2 + 2HCl + S}}}$
1. +2 to +3
2. +3 to +2
3. 0 to +2
4. +3 to 0
Which of the following methods can be used to separate blood cells from plasma?
1. Centrifugation.
2. Filtration.
3. Chromatography.
4. Distillation.
Which of the following statements about ionic radius is correct? Ionic radius
1. Increases as nuclear charge increases.
2. Decreases as nuclear charge increases.
3. Decreases as nuclear charge decreases.
4. Remains constant as nuclear charge increases.
Analysis of a hydrocarbon shows that it contains 0.93g of carbon per gram of the compound. The mole ratio of carbon to hydrogen in the compound is [H=1.0 C=12.0]
1. 1.1
2. 1.2
3. 2.1
4. 2.3
The law of definite proportions states that
1. Pure samples of the same compound the same element combined in the same proportion by mass.
2. Pure samples of substances are in the same proportion by Mass.
3. Chemical compounds are pure because they contain the same elements.
4. matter can neither be created nor destroyed.
What is the relative molecular mass of a compound which has empirical formula ${\textstyle {\ce {CH2O}}}$ ${\textstyle {\ce {CH2O}}}$ ? [H=1.0, C=12.0, O=16.0]
1. 42
2. 45
3. 126
4. 180
Atoms are electrically neutral because they
1. Do not conduct electricity.
2. Contain equal number of protons and electrons.
3. Are composed of neutrons and electrons.
4. cannot be attracted by electromagnetic field.
Common salt (NaCl) is used for preserving foods. Which of the following properties could be used to determine its purity before use?
1. Solubility in water.
2. Melting point.
3. Relative density.
4. Crystalline nature.
Which of the following electron configurations represents the transition element chromium( ${\textstyle {\ce {_24Cr}}}$ ${\textstyle {\ce {_24Cr}}}$ ) ?
1. ${\textstyle {\ce {1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^4}}}$
2. ${\textstyle {\ce {1s^2 2s^2 2p^6 3s^2 3p^6 3d^6}}}$
3. ${\textstyle {\ce {1s^2 2s^2 2p^6 3s^2 3d^4 4s^1}}}$
4. ${\textstyle {\ce {1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5}}}$
The atomic number of an isotope of hydrogen is equal to its mass number because it
1. Has a totally filled valence shell.
2. Has a high charge to mass ratio.
3. Does not contain neutrons.
4. Exhibits isotopy.
The total number of shared pair of electrons in the compound below is
1. 5
2. 6
3. 10
4. 12
The bonding pair of electrons in a hydrogen chloride molecule is pulled toward the chlorine atom because
1. Chlorine has a larger atomic size.
2. Chlorine has a larger atomic mass.
3. Chlorine is more electronegative.
4. There is no bonding orbitals within the hydrogen atom.
Which of ${\textstyle {\ce {CO2}}}$ ${\textstyle {\ce {CO2}}}$ the following properties would not influence electrovalent bond formation?
1. van der Waal’s forces.
2. Ionic attraction.
3. Dipole attraction.
4. Covalent bonding.
Which of the following properties would not influence electrovalent bond formation?
1. Electronegativity.
2. Electron affinity.
3. Ionization potential.
4. Catalytic ability.
Particles in a solid exhibit
1. Vibrational motion only.
2. Vibrational and translational motion.
3. Vibrational and random motion.
4. Ranfom and translational motion.

Chemistry 2 - Theory Questions

Section A - For All Candidates

1. 1. Define the term fermentation.
  2. Name the catalyst that can be used for this process.
2. Name two factors which determine the choice of an indicator for an acid base titration. (c) Consider the following reaction equation:
3. Consider the following reaction equation: ${\ce {Fe + H2SO4 -> FeSO4 + H2.}}$ Calculate the mass of unreacted iron when 5.0g of iron reacts with 10 $cm^{3}$ of 1.0 $moldm^{-3}$ ${\ce {H2SO4}}$ , [Fe=56.0]
4. Name one:
  1. Heavy chemical used in electrolytic cells;
  2. Fine chemical used in textile industries.
5. Explain briefly how a catalyst increases the rate of a chemical reactions.
  1. Write the chemical formula for the product formed when ethanoic acid reacts with ammonia
  2. Give the name of the product formed in 1(f)(i).
6. List three properties of Aluminum that makes it suitable for the manufacture of drink cans.
7. State two industrial uses of alkylalkanoates.
8. Name two steps involved in the crystallization of a salt from its solution.
9. List two effects of global warming.

Section B

1. 1. State the collision theory of reaction rates.
  2. Using the collision theory, explain briefly how temperature can affect the rate of a chemical reaction.
2. 1. Sketch a graphical representation of Charles’ law.
  2. Calculate the volume of oxygen that would be required for the complete combustion of 2.5 moles of ethanol at s.t.p. [Molar volume at s.t.p.= 22.4 $dm^{3}$ ]
3. 1. Define esterification.
  2. Give two uses-of alkanoates.
  3. Give the products of the alkaline hydrolysis of ethyl ethanoate.
4. A tin coated plate and a galvanized plate were exposed for the same length of time.
  1. Which of the two plates corrodes faster?
  2. Explain briefly your answer in 2 (d)(i).
1. 1. Draw the structure of the sixth member of the alkenes.
  2. Calculate the relative molecular mass of the sixth member of the alkene.
  3. State one difference between cracking and reforming in the petroleum industry. [H=1. C=12]
2. 1. Define the term enthalpy of neutralization.
  2. Describe briefly how the enthalpy of neutralization of the reaction of dilute hydrochloric acid and aqueous potassium hydroxide could be determined.
3. An electrochemical cell is constructed with copper and silver electrodes.
  1. State which of the electrodes will be the I. Anode II. Cathode.
  2. Give the reason for your answer in 3(c)(i).
  3. State the type of reaction occurring at each electrode.
  4. Write a balanced equation for the overall cell reaction.
4. 1. Name the compound formed when iron is exposed to moist air for a long time.
  2. Write a balanced chemical reaction for the reaction in 3(d)(i).
  3. Name one ore of iron.

Section C - For Candidates in Nigeria, Sierra Leone, The Gambia and Liberia

1. 1. Draw and label a diagram for the laboratory preparation of a dry sample of sulphur(IV)oxide
  2. Write a balanced chemical equation for the reaction in 4(a)(I)
  3. State the precaution that must be taken in the preparation of the gas stated in 4(a)(i)
  4. Give a reason why the precaution stated in 4(a)(ii) must be taken.
2. 1. State Dalton’s law of partial pressures.
  2. The volume of a sample of methane collected over water at a temperature of 12°C and a pressure of 700mmHg was 30 $cm^{3}$ . Calculate the volume of the dry gas at s.t.p [saturated vapor pressure of water at 12°C is 10mmHg.
3. 1. Write an equation for the reaction between chlorine and water.
  2. Why does litmus paper turn red when put in the resulting solution in 4(c)(i)?
4. 1. State the trend in the boiling points of chlorine, bromine and iodine.
  2. Explain briefly why water has a higher boiling point than ammonia.
1. 1. State two industrial uses of hydrogen.
  2. Consider the equation below: ${\textstyle {\ce {Mg(HCO3)2{}_{(aq)}-> MgCO3{}_{(g)}+ H20{}_{(l)}+ CO2{}_{(g)}}}}$ I. State the type of hardness of water being removed as shown by the above equation. II. Give two disadvantages of hardness of water.
2. 1. In the extraction of aluminum by electrolysis, graphite electrodes are used. State the disadvantages of using this type of electrode.
  2. Calcium oxide reacts with water to form slaked line: I. Write a balanced equation for this reaction; II. State one use of slaked line.
3. 1. What is meant by saponification?
  2. List the raw materials needed for the manufacture of soap.
  3. Name the main by-product obtained from the manufacture of soap.
4. With the aid of chemical equations explain briefly how iron is extracted in the blast furnace using iron ore, coke and limestone as raw materials at the:
  1. Bottom of the furnace;
  2. Middle of the furnace;
  3. Top of the furnace

Chemistry 3 - Practical Questions

All your burette readings (initials and final) as well as the size of your pipette must be recorded but no account of experimental procedure is required. All calculations must be done in your answer booklet.

A is a solution of potassium tetraoxomanganate(VII). B is a solution of iron(II)chloride containing 4.80g of the salt in 250 $cm^{3}$ $cm^{3}$ of solution.
1. Put A into the burette. Pipette 20.0 $cm^{3}$ or 25.0 of B into a conical flask. add 20.0 $cm^{3}$ of ${\textstyle {\ce {H2SO4(aq)}}}$ 3 and titrate with A. Repeat the titration to obtain concordant titre values. Tabulate your results and calculate the average volume of A used. The equation of the reaction is: ${\textstyle {\ce {MnO4{}_{(aq)}+ 5Fe^2+{}_{(aq)}+ 8H^+{}_{(aq)}-> Mn^2+{}_{(aq)}+ 5Fe^3+{}_{(aq)}+ 4H2O{}_{(l)}}}}$
2. From your results and the information provided, calculate the:
  1. Concentration of B in $moldm^{-3}$
  2. Concentration of A in $moldm^{-3}$
  3. Number of moles of ${\textstyle Fe^{2+}}$ in the volume of B pipetted. [ ${\textstyle {\ce {FeCl2}}}$ = 127 ${\textstyle gmol^{-1}}$ ]
Credit will be given for strict adherence to the instruction, for observations precisely recorded and for accurate inferences. All tests, observations and inferences must be clearly entered in the booklet in ink at the time they are made.
C and D are inorganic salts. Carry out the following exercises on them. Record your observations and identify any gas(es) evolved. State the conclusions you draw from the result of each test.
1. Put all of C in a test tube and about 5 $cm^{3}$ $cm^{3}$ of distilled water. Shake thoroughly and test the resulting solution with litmus paper. Divide the solution into three portions.
  1. To the first portion add ${\textstyle {\ce {NaOH(aq)}}}$ in drops, then in excess.
  2. To the second portion, ${\textstyle {\ce {NH3(aq)}}}$ in drops, then in excess.
  3. To the third portion, add ${\textstyle {\ce {AgNO3(aq)}}}$ followed by ${\textstyle {\ce {HCl(aq)}}}$
  4. Put all of D in a test tube and add about 5 $cm^{3}$ of distilled water. Shake thoroughly and feel the test tube.
  5. To about 2 $cm^{3}$ of the solution, add ${\textstyle {\ce {HCl(aq)}}}$ .
State the observation that would be made when each of the following reactions is carried out in the laboratory:
1. Addition of 2 $cm^{3}$ of bench ${\textstyle {\ce {H2SO4(aq)}}}$ to 2 $cm^{3}$ of barium chloride solution.
2. Addition of 2 $cm^{3}$ of dilute hydrochloric acid to 1g of powered iron(II) sulphide (FeS).
3. Addition of 2 $cm^{3}$ of dilute hydrochloric acid to 1g of iron filings and allowed to stand for sometimes.