WAEC Chemistry 2017 Past Questions

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Question 1

Which of the following species determines the chemical properties of an atom?

A.Electron
B.Neutron
C.Nucleus
D.Proton

Objective

Question 1

(a)(i) What is an acid-base indicator?

(ii) Give one example of an acid-base indicator.

(b) State the property exhibited by nitrogen(IV) oxide in each of the following equations:,

(i) 4Cu + 2NO\(_2\) -> 4CuO + N\(_2\) (ii) H\(_2\)O + 2NO\(_2\) --> HNO\(_3\) + HNO\(_2\)

(c)(i) Define enthalpy of combustion..

(ii) State why the enthalpy of combustion is always negative.

(d)(i) Distinguish between a primary cell and a secondary cell.

(ii) Give an example of each of the cells stated in I (d)(i).

(e) Define the term mole.

(f) Calculate the amount of hydrochloric acid in 40.0 cm\(^3\) of 0.40 moldm\(^{-3}\) dilute HCl.

(g) Name two substances which can be used as electrodes during the electroylsis of acidified water.

(h) List two forces of attraction that can exist between covalent molecules.

(i) Name the products formed when butane undergoes incomplete combustion.

(j) Write the electron configuration of \(_{26}\)Fe\(^{3+}\)

Theory

Question 2

The following glasswares are used to measure the volume of liquids EXCEPT

A.graduated beaker
B.pipette
C.test tube
D.burette

Objective

Question 2

(a)(i) 1. State the periodic law.

2. What is meant by the term periodic property of elements?

(ii) List three properties of an element which show periodicity.

(iii) Explain briefly how each of the properties listed in (a)(i) in varies across the period.

(b) Defulle relative atomic mass.

(c)(i) What phenomenon is exhibited by an element Z which exist as \(^{35}_{17}Z\) and \(^{37}_{17}X\)

(ii) What accounts for the difference in the mass numbers of the element Z?

(iii) Calculate the relative atomic mass of Z if the percentage abundance of \(^{37}_{17}Z\) is 75%

(d)(i) State the method used for collecting each of the following gases: I. CO II. HCI III. H\(_2\)

(ii) Give a reason for your answer stated in (d)(i) I and II

Theory

Question 3

Pauli exclusion principle is related to

A.quantity of electrons in the valence shell
B.filling the orbitals with lower energy first
C.the filling of degenerated orbitals
D.quantum numbers of electrons

Objective

Question 3

(a) Write the molecular formula of X.

(i) What type of reaction is represented by the equation?

(ii) Consider the following reaction equation: C\(_{12}H_2\) \(\to\) X + C\(_8\)H\(_{18}\)

(iii) Draw the structure of two isomers of X.

(iv) Name the isomers drawn in (a)(iii).

(v) Write a balanced equation for the reaction between X and hydrogen.

(b) Describe one test for fats.

(c) Sulphur (IV) oxide is converted to tetraoxosulphate (VI) acid according to the following equation: 2SO\(_{2(g)}\) + O\(_{2(g)}\) + 2H\(_2\)O\(_{(l)}\) \(\to\) 2H\(_2\)OSO\(_{4(aq)}\). If 1.5 moles of oxgen reacts with sulphur (IV) oxide, calculate the mass of tetraoxosulphate (VI) acid produced. [H = 1.0; O = 16.0; S = 32.0].

(d) Consider the following neutralization reaction:

CH\(_3\)COOH + NaOH \(\to\) CH\(_3\)COONa + H\(_2\)O; \(\bigtriangleup\)H\(_1\)

CH\(_3\)COOH + NH\(_4\)OH \(\to\) CH\(_3\)COONH\(_4\) + H\(_2\)O; \(\bigtriangleup\)H\(_2\)

NaOH + HCl \(\to\) NaCl + H\(_2\)O \(\bigtriangleup\)H\(_3\)

(i) Arrange the enthalphy changes for the reactions in order of increasing magnitude.

(ii) Explain briefly your order in (d)(i).

(e) Consider the following substances. Cu\(_{(s)}\), BeCl\(_2\), NaH\(_{(s)}\), HF\(_{(s)}\)and CCl\(_{4(l)}\). State the substance(s) which;

(i) can conduct electricity;

(ii) is/are soluble in water.

Theory

Question 4

The species with no electron in the 3d-orbital is

A.\(Zn^{2+}\)
B.\(Sc^{3+}\)
C.Cu
D.\(Mn\)

Objective

Question 4

(a)(i) Describe briefly the industrial preparation of ammonia.

(ii) Write a balanced equation for the reaction in (a)(i).

(iii) State one way of increasing the yield of ammonia in 4(a)(i).

(iv) State two uses of ammonia.

(b) Describe briefly, one chemical test for each of the following gases in the laboratory: (i) hydrogen; (ii) carbon (IV) oxide; (iii) oxygen.

(c)(i) State the composition of water gas.

(ii) List two uses of water gas.

(d) Describe briefly a simple experiment to determine the type of hardness in a sample of water.

Theory

Question 5

The seperation of Nitrogen from oxygen using fractional distillation of air is possible because

A.nitrogen is less dense than oxygen
B.oxygen is more reactive than nitrogen
C.of the difference in their boiling points
D.they belong to the same period

Objective

Question 5

(a)(i) Describe briefly how trioxonitrate (V) ions could be tested for in the laboratory.

(ii) State two uses of each of the following compounds: I. sodium chloride; II. sodium trioxocarbonate (IV).

(b) Write balanced equations for the reactions involved in the extraction of iron in the blast furnace.

(ii) State Faraday's first law of electrolysis.

(iii) State two applications of electrolysis.

(c) Concentrated tetraoxosulphate (VI) acid is added to sugar crystals in a beaker. State what would be observed. Explain briefly your answer.

(d) Write an equation for the reaction of zinc powder with:

(i) dilute tetraoxosulphate (VI) acid;

(ii) concentrated tetraoxosulphate (VI) acid.

(e) What property of concentrated tetraoxosulphate (VI) acid is shown in (d)(ii)

Theory

Question 6

The purity of a solid sample can best be determined by its

A.boiling point
B.melting point
C.conductivity
D.solubility

Objective

Question 7

The mass of one mole of \((NH_{4})_{2}CO_{3}\) is [O=16.0, N=14.0, C=12.0, H=1.0]

A.66.0g
B.76.0g
C.80.0g
D.96.0g

Objective

Question 8

Atomic orbital is

A.the circular path through which electrons revolve round the nucleus
B.a region around the nucleus where electrons are most likely to be found
C.the path around the nucleus through which electrons move
D.the path around the nucleus through which protons move

Objective

Question 9

The property of elements which increases down a group of the periodic table is

A.electronegativity
B.electron affinity
C.ionic radius
D.ionization energy

Objective

Question 10

The reason for the decrease in the atomic size of elements across a period is that

A.nuclear charge increases while the outermost electrons are drawn closer to the nucleus
B.nuclear charge decreases while the outermost electrons are drawn closer to the nucleus
C.valence electrons increase across the period while the valence shell remains constant
D.nuclear charge decreases while the distance of the valence shell from the nucleus is increasing

Objective

Question 11

The oxidation number of nitrogen in \(Pb(NO_{3})_{2}\) is

A.+2
B.+3
C.+4
D.+5

Objective

Question 12

Which of the following arrangements indicates the correct decreasing order of ionization energy of period 3 elements?

A.Na, Al, P, Cl
B.Cl, P, Al, Na
C.Na, P, Cl, Al
D.Al, Na, P, Cl

Objective

Question 13

Which of the following metals has the strongest metallic bond?

A.\(_{13}Al\)
B.\(_{19}K\)
C.\(_{12}Mg\)
D.\(_{11}Na\)

Objective

Question 14

Which of the following substances does not have van der Waals' forces?

A.Copper
B.Graphite
C.Neon
D.Iodine crystals

Objective

Question 15

The oxidation number of X in \(XO_{4}^{3+}\) is

A.+1
B.+3
C.+4
D.+5

Objective

Question 16

The ionization energy is affected by the following factors except

A.distance of the outermost electron(s) from the nucleus
B.size of the positive nuclear charge
C.ability to attract shared electron(s)
D.screening effect of the inner electron(s)

Objective

Question 17

Which of the following statements is correct?

A.Covalent compounds would readily ionize in solution
B.Covalent compounds consist of ions
C.Hydrogen bond is formed between a metal and a non-metal
D.Ionic compounds in solution would conduct electricity

Objective

Question 18

The bond angle in tetrahedral molecules such as tetrachloromethane is

A.180.0°
B.109.5°
C.105.5°
D.90.0°

Objective

Question 19

The properties of a good primary standard include the following except

A.high molecular mass
B.low molecular mass
C.high degree of purity
D.readily available

Objective

Question 20

The use of diamond in abrasives is due to its

A.high melting point
B.hardness
C.octahedral shape
D.durability

Objective

Question 21

Which of the following statements about endothermic reaction is correct?

A.Activation energy is high
B.A catalyst is required
C.It occurs reversibly
D.Heat energy is absorbed

Objective

Question 22

A 0.1\(moldm^{-3}\) solution of sodium hydroxide was diluted with distilled water to 0.001\(moldm^{-3}\). What is the dilution factor?

A.1000.00
B.100.00
C.10.00
D.0.01

Objective

Question 23

Graphite and Diamond are similar in that they

A.have octahedral shape
B.have same density
C.form carbon(IV) oxide on combustion
D.conduct electricity

Objective

Question 24

In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with

A.the solvent
B.dissolved solute particles
C.the saturated solution
D.insoluble solute particles

Objective

Question 25

The number of atoms present in 2.5moles of a triatomic gas is equivalent to [1mole = \(6.02\times 10^{23}\)]

A.\(2.5\times 10^{23}\)
B.\(1.5\times 10^{23}\)
C.\(1.5\times 10^{24}\)
D.\(2.5\times 10^{24}\)

Objective

Question 26

When Magnesium reacts with oxygen, heat is

Theory

Question 27

Which of the following gases is not acidic?

A.\(SO_{3}\)
B.\(NO_{2}\)
C.\(Co_{2}\)
D.CO

Objective

Question 28

A hydrocarbon contained 14.3% hydrogen. The empirical formula for the hydrocarbon is [H= 1.0, C= 12.0]

A.\(CH\)
B.\(CH_{2}\)
C.\(CH_{3}\)
D.\(CH_{4}\)

Objective

Question 29

Which of the following statements is NOT a chemical property of an acid?

A.Evolution of ammonia when heated with ammonium salts
B.Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt
C.Formation of salt and water with alkalis
D.Formation of salt and hydrogen gas with reactive metals

Objective

Question 30

Halogens generally react with metals to form

A.alkalis
B.acids
C.bases
D.salts

Objective

Question 31

Potassium Chloride solid does not conduct electricity because

A.it is a covalent compound
B.strong cohesive forces make its ions immobile
C.strong cohesive force makes its molecule immobile
D.each of potassium and chlorine structures contain noble gas structure

Objective

Question 32

When water was added to a white anhydrous substance X, the colour changed to blue. X is

A.\(CuSO_{4}\)
B.\(FeSO_{4}\)
C.\(Na_{2}SO_{4}\)
D.\(PbSO_{4}\)

Objective

Question 33

Solubility curve can be used in the determination of the

A.amount of crystals formed
B.amount of solvent that can be recovered
C.amount of solid drugs in a given solution
D.temperature of the solution

Objective

Question 34

If 0.2g of a salt is required to saturate 200\(cm^{3}\) of water at room temperature, what is the solubility of the salt?

A.0.2\(gdm^{-3}\)
B.1.0\(gdm^{-3}\)
C.2.0\(gdm^{-3}\)
D.5.0\(gdm^{-3}\)

Objective

Question 35

The property of a chemical reaction that is affected by the presence of a catalyst is

A.activation energy
B.free energy
C.equilibrium position
D.enthalpy change

Objective

Question 36

Soluble salts can be prepared by the following methods except

A.neutralization
B.reaction of an acid with trioxocarbonate(IV) salt
C.double decomposition
D.reaction of an acid with electropositive metals

Objective

Question 37

Chemical reactions occurs when the colliding reactants have energy that is

A.less than the activation energy
B.greater than the activation energy
C.greater than the energy of the product
D.less than the energy of effective collision

Objective

Question 38

The common feature of reactions at the anode is that

A.electrons are consumed
B.ions are reduced
C.oxidation is involved
D.the electrode dissolves

Objective

Question 39

Consider the following reaction equation: \(2NO_{(g)} + O_{{2}{(g)}} \to 2NO_{{2}{(g)}}\). What is the change in the oxidation number of nitrogen?

A.+2 to 0
B.+2 to -2
C.+2 to +4
D.+4 to +2

Objective

Question 40

Which of the following factors characterize members of the same homologous series?

A.The chemical property change gradually throughout the series
B.physical properties of members are similar
C.They have the same molecular formular
D.Successive members undergo changes in molecular formula by \(CH_{2}\)

Objective

Question 41

Calculate the mass of copper deposited if a current of 0.45A flows through \(CuSO_{4}\) solution for 1hour 15mins. [Cu=64.0, S= 32.0, O =16.0, 1F= 96500C]