WAEC Chemistry Questions and Answers for 2022/2023 (Theory and Objectives)

This post will supply you with WAEC Chemistry Questions and Answers, WAEC Chemistry Questions and Answers, WAEC Chemistry Questions, and everything you need to know about the 2022 WAEC Chemistry Examination. Chemistry Paper 1 (Objective) and Chemistry Paper 2 (Essay) can be found here.

For today’s Chemistry Answers, go to the bottom of the page.

The WAEC Chemistry questions are listed below. Read these and prepare to do well on the WAEC Chemistry exam.

The West Africa Examination Council (WAEC) is a Nigerian examination board that holds exams in May/June and November/December for the Senior Secondary Certificate Examination and the General Certificate in Education, respectively.

WAEC Chemistry Questions and Answers 2022

Note: The following answers are for the WAEC in 2021.

(1a)

A structural formula consists of symbols for the atoms connected by short lines that symbolize chemical bonds, whereas a molecular formula consists of chemical symbols for the ingredient followed by numeric subscripts representing the number of atoms of each element present.

 

(1b)

I The effect of screening

(ii) Atomic size

(iii) Alteration of the nuclear power plant

 

(1c)

I The reaction must be reversible and able to go both forward and backward.

(ii) At equilibrium, all reactants and products are present.

(1d)

B I

(ii) Of the three, it has the lowest ionization energy.

(1e)

Graham’s law of diffusion asserts that a gas’s rate of diffusion is inversely proportional to the square root of its density, assuming all other variables remain constant.

 

(1f)

Mg(NO3)2 I Na2SO4 (ii) Na2SO4 (ii) Na2SO4 (ii)

CaCO3 (ii)

(1g)

I Condensational polymer of protein

(ii) Perspex – a different type of polymer

Nylon – Condensation polymer (iii)

 

(1h)

The half distance between the nuclei of two covalently bound atoms is known as the atomic radius.

 

(1i)

Because ethanol has a stronger force of attraction than propane, which has a weak van der Waal’s force, it has a higher boiling point.

 

(1j)

I It assists in food digestion.

(ii) It helps enzymes work better.

(iii) It regulates nutrition availability.

 

The WAEC Chemistry Questions are listed below. Go over them and be prepared to do well in your WAEC 2021 Chemistry Exam.

1. What condition favours the formation of the product for the endothermic reaction, N2O4(g) —><—– 2NO2(g)

A. Decrease in pressure

B. A decrease in volume

C. An increase in pressure

D. A constant volume

ANSWER: A ( Decrease in pressure)

2. How many alkoxy alkanes can be obtained from the molecular formula C4 H4O4

A. 1

B. 2

C. 3

D. 4

ANSWER: C (3)

3. Element Y has two isotopes Y and Y present in the ratio 1:3. The relative atomic mass of Y would be

A. 20.5

B. 21

C. 21.5

D. 22

ANSWER: C (21.5)

4. 100.0g of KClO3 was added to 40.0 cm^3 of water to give a saturated solution at 298K. If the solubility of the salt is 20.0 moldm^-3 at 298K, what percentage of the salt is left undissolved? {K= 39, Cl = 35.5, O = 16}

A. 80%

B. 60%

C. 5%

D. 2%

5. Elements X and Y have electronic configuration 1S22S22P4 and 1S22S22P63S23P1 respectively. When they combine the formula of the compound formed is

A. XY

B. Y2X3

C. Y2 X3

D. Y X2

ANSWER: B (Y2X3)

Recommended: WAEC Timetable

6. A solution of 0.20 mole of NaBr and 0.20 mole of MgBr2 in 2.0 dm3 of water is to be analysed. How many moles of Pb(NO)2 must be added to precipitate all the bromide as insoluble PbBr2

A. 0.30 mol

B. 0.10 mol

C. 0.20 mol

D. 0.40 mol

ANSWER: A (0.30 mol)

7. Na2CO3 + HCl —-> NaHCO3 + NaCl. The indicator most suitable for this reaction should have pH equal to.

A. 3

B. 5

C. 7

D. 9

ANSWER: D (9)

8. A satuarted solution of silver trioxocarbonate (IV), was found to have concentration of 1.30 x 10-5 moldm-3 . The solubility product of the trioxocarbonate (IV) is

A. 8.79 x 10-15

B. 1.69 x 10-10

C. 1.82 x 10-11

D. 9.84 x 10-10

ANSWER: A (8.79 x 10-15)

9. When platinum electodes are used during the electrolysis of copper (II) tetraoxosulphate (IV) solution, the solution gets progressive

A. Acidic

B. Basic

C. Neutral

D. Atmospheric

ANSWER: A (Acidic)

10. Tetraoxosulphate (VI) ions are final test using

A. acidified silver nitrate

B. acidic barium chloride

C. lime water

D. dilute hydrochloric acid

ANSWER: D (dilute hydrochloric acid)

WAEC Chemistry Questions and Answers 2022 Theory Questions

PAPER 2 (ESSAY)

SECTION A

1. Identify the solid remaining when each of the following is heated.
(a) lithium trioxonitrate (V)
(b) potassium trioxonitrate (V)
(c) calcium trioxonitrate (V)

2. (a) When calcium oxide and coke are heated in an electric furnace, the products are carbon (ii) oxide and calcium carbide (CaC2), write the equation for this reaction.

(b) The addition of water to calcium carbide leads to the formation of calcium hydroxide and ethyne. Write the equation for the production of ethyne.

3. Calculate the percentage by mass of silicon tetrachloride. [2 marks]
4. Ammonia, NH3, and phosphine, Ph3, are the hydrides of the first two elements in group 5.
(a) Draw a dot and cross diagram for the ammonia molecule. [2 marks]
(b) Sketch and explain the shape of the ammonia molecule. [3 marks]

5. The first ionization energy of chlorine is +1260KJmol-1.
(a) Define the term first ionization energy.
(b) State and explain the general trend in the values of the first ionization energy for the elements across the period, sodium to argon in the periodic table.

6. Compound A consisting of carbon and hydrogen only. The compound was found to contain 80% carbon by mass.
(a) Calculate the empirical formula of compound A using the data above.
(b) The relative molecular mass of compound A was found to be 30.
Use this information to deduce the molecular formula of compound A.
[H = 1.00 C = 12.00]

7. State two factors other than a change in temperature or the use of a catalyst that influence the rate of a chemical reaction.

SECTION B

1. (a) Two elements represented by the letters Q and R have atomic numbers 9 and 12 respectively.
(i) Write the election configuration of R.
(ii) To what group does Q belong in the periodic table.
(iii) Write the formula of the compound formed when Q combines with R.
(iv) Explain briefly, why Q is a good oxidizing agent.
(v) State whether R would be expected to form acidic or basic oxide.
(b) (i) State two assumptions of the kinetic theory of gases.
(ii) When some solids are heated, they change directly into the gaseous state. What name is given to this phenomenon?
(iii) List two substances which exhibit the phenomenon mentioned in (ii).
(iv) Write an expression to show the mathematical relationship between the rate of diffusion of a gas and its vapour.

2. An aqueous solution has a pH of 4.0.
(a) (i) What is the hydrogen ion concentration of the solution?
(ii) What effect will it have on litmus paper?
(iii) Which of the following salt solutions would have the same effect on litmus? Give a reason for your answer. NH4Cl(aq); NaCl(aq) ; CH3OON(aq).
(b) (i) Differentiate between a fine chemical and a heavy chemical.
(ii) Name two sources of air pollution.
(iii) Suggest one way of reducing air pollution in cities

3. (a) (i) Explain briefly the fermentation process.
(ii) Write a balanced equation for the fermentation of glucose.
(iii) What substance must be added to glucose solution to ferment it?
(iv) Explain briefly why tightly corked glass filled to the brim with palm wine shatters on standing.
(b) State one industrial application of each of the following methods of separation:
(i) Crystallization;
(ii) Fractional distillation.
(c) Explain the following terms:
(i) Saponification;
(ii) Esterification.
(d) Write a balanced equation to illustrate each of the terms in (c).
(e) i) What is hydrocarbon compound?
(ii) Name two principal sources of hydrocarbons.

WAEC Chemistry Essay and Objective 2022 (EXPO)

The above questions are likely WAEC Chemistry repeated questions and answers, rather than 2022 WAEC Chemistry questions and answers.

These are just practice questions. During the WAEC Chemistry examination in 2021, the WAEC Chemistry exhibition will be posted on this page. For the answers, keep checking and refreshing this page.

Today’s Chemistry Questions and Answers

Answers to Chemistry Objectives (2020 Answers)

1-10: CACDBDADAD
11-20: AADCDABBCD
21-30: BACBCCBCAC
31-40: CBACBCDBAD
41-50: DBBDCBCCCB

(1ai)
Faraday’s First Law of Electrolysis states that the chemical deposition due to the flow of current through an electrolyte is directly proportional to the quantity of electricity (coulombs) passed through it.

(1aii)
Strong electrolytes ionize completely (100%), while weak electrolytes ionize only partially.

(1b)
CHEMICAL PROPERTY OF EHYNE
– COMBUSTION REACTION: Ethyne burns in air with a luminous smoky flame and hence used for lightening purpose.
2C2H2 + 5O2 —–> 4CO2 + 2H2O + heat

(1c)
Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms.

(1cii)
CH3COOH + CH3OH–>CH3COOCH3 + H2O

(1ciii)
methly ethanoate

(1d)
By removing the main product continuously.

(1e)
Mzn = 3.75g
Mzn = 65.0g/mol
n= m/M=3.75/65.0
n=0.0577mole
nH² =0.0577mole because the mole ratio is the same
np =n*L
np=0.0577*6.02*10^23
np=3.47*10^22 moles

(1d)
Addition of catalysis I;e it catalyzed by a high concentration of hydrogen ion

(1f)
Flooding

(1gi)
Reaction C

(1gii)
Zinc (from + 2 to + 4)

(1hi)
(i)Each spectral line is caused by one electron
(ii)Electron can exist only in circular orbit of definite quantum energy.

(1hii)
It could not account for the spectrum at note complicated atoms

(1i)
(i)Temperature of the reacting system
(ii)Pressure of the reacting system
(iii)Concentration of the reacting system

(1j)
Both liberate carbon(iv) oxide
One produce a chloride salt , the other produce an ethronate salt

2ai)
The relationship between the compounds A and B is that they have similar chemical properties

(2aii)
– A : Trans-1,2-dichloroethene
– B : Cis-1,2-dichloroethene

(2aiii)
Their chemical properties will be the same

(2aiv)
The reason is because they are geometric isomers. Geometric isomers have the same chemical properties but different physical properties.

2bi)
(i) Temperature remains constant during boiling
(ii) There is change of state during boiling

(2bii)
I – It will increase the boiling point of water.
II – It will reduce the boiling point of water.

(2biii)
Boiling occurs at a specific temperature While Evaporation occurs at almost all temperatures.

(2ci)
An unsaturated solution is one that contains less than the maximum amount of solute that can dissolve at a given temperature While A saturated solution is one that contains maximum of solute that can be dissolved in it at that temperature.

(2cii)
(i) By increasing the temperature of the solution.
(ii) By increasing the amount of the solute.

(2ciii)
Temperature.

(2di)
Mole is a standard scientific unit for measuring large quantities of very small entities such as atoms, molecules, or other specified particles

(2dii)
MgO(s)+2HCl(aq) —> MgCl(aq)+H2O(l)
From the equation of reaction; 1 mole of MgO = 2 moles of HCl
Hence n = cv/100
where c = 0.1moldm-³; v = 25.0cm³
No of mole of HCl = n = 0.1×25/1000
= 2.5 x 10-³ moles
Hence the no of moles ofMgO required = 2.5/2 x10-³
But n = m/M = reacting mass/ Molar mass —> m = nM = 1.25×10-³ x 40
= 50 x 10-³ = 0.05g of MgO.

(2e)
(i) They are malleable
(ii) They are ductile
(iii) They are good conductors of heat and electricity

=====================

3ai)
Draw the diagram

(3aii)
I. Activation Energy = (210 – 100)KJ = 110K
II. Hp – HR = ΔH
54 – 100 = -46KJ

(3aiii)
Q2(g) + R2(g) –> 2QR(g)

(3aiv)
Exothermic reaction.

(3av)
The heat content of the reactant is higher than that of the product.

(3bi)
E7 – 1s² 2S² 2P³
F9 – 1s² 2S² 2P⁵
G12 – 1S² 2S² 2P⁶ 3S²
H13 – 1S² 2s² 2P⁶ 3S² 3P¹

(3bii)
I. G and H
II. H
III. F
IV. GF2

(3ci)
Isotopy is the existence of an element in more than one physical form with the same atomic number but different atomic masses.

(3d)
(i) Atoms
(ii) Molecules
(iii) ions

WAEC Chemistry Questions and Answers
WAEC Chemistry Questions and Answers
WAEC Chemistry Questions and Answers

5ai)
(i) Ammonia (NH3)
(ii) Hydrogen chloride gas(HCl)

(5aii)
To show that hydrogen chloride is extremely soluble in water.

(5aiii)
Fill a round-bottomed flask with dry hydrogen chloride through a tube A and air through another tube B. Add a few drops of water through B and close the tubes. Invert the flask into a trough of water containing blue litmus solution. The water turns red.

(5bi)
Petrochemical industries.
Pharmaceutical industries.

(5bii)
(i) Pollution of water bodies by chemical waste.
(ii) Pollution of air.
(iii) Radioactive particles are released.

(5ci)
(i) Coke.
(ii) Coal tar.
(iii) Coal gas.

(5cii)
(i) Coal gas –> Importsmt gaseous fuel.
(ii) Coke –> Used as a reducing agent.

(5di)
(i) Calcium tetraoxosulphate(vi)
(ii) Calcium hydrogentrioxocarbonate(iv)

(5dii)
(i) By boiling.
(ii) Addition of caustic Soda.

(5diii)
(i) Hard water contains dissolved minerals and therefore tastes better.
(ii) The calcium salts on hard water help animals to build strong teeth and bones

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Tips to Pass WAEC Chemistry Questions

1. Concentrate on your studies.

Everyone understands that success comes from hard work. Make sure to study the West Africa Examination Council’s recommended chemistry texts (WAEC).

This will allow you to see the majority of the questions that will be asked on the day of your WAEC Chemistry test.

Let me emphasize unequivocally that questions are derived from textbooks suggested by WAEC, not from heaven.

2. Review WAEC Chemistry Questions from the Past

In order to create new questions, WAEC frequently selects questions from prior years. Past WAEC Chemistry questions can offer you an idea of how the questions are set for WAEC Chemistry.

3. Begin planning for WAEC 2022:

Don’t squander your time. After you’ve obtained your textbooks and practice questions, it’s time to start reading. You will do well on WAEC 2022 Chemistry if you start reading and practicing early.

4. Try to understand and solve every example and exercise in your textbooks.

Secondary school pupils have an undesirable habit of skipping exercises and even examples while studying textbooks.

They were so enamored with notebooks that they asked, “Can I read my Chemistry notebook and pass WAEC 2022?” Don’t be afraid to try exercises; they’re there to assist you. Face it and conquer it!

5. Practice on a regular basis

Don’t get frustrated if particular topics irritate you; keep practicing until you’ve mastered them all. Never say never and never give up. Continue to push….

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