Mostly Repeated WAEC Past Questions and Answers on Chemistry

 Mostly Repeated WAEC Past Questions and Answers on Chemistry

WAEC Past Questions and Answers on Chemistry| West African Examination Council Past  Questions 2020— I believe that you’re here because you don’t know the nature of how exams are being set by WAEC. If you don’t, then you’re at the right place.

In this guide, we will talk extensively on WAEC past questions and answers for chemistry, show you possible questions that may likely fall into the exams paper in the proceeding year.

Not only that, you’ll be given adequate instructions on how to answer questions on WAEC

The WAEC past questions and answers are mostly repeated year after year, which is why you have to read this guide carefully till the end and take notice of those questions.

Most times, I hear students giving complains about how hard the questions is, reason behind it is that they failed to study using our guide.

I believe if you’re reading this, you will definitely want to pass your exams with flying colours. See more details on the instructions and guidelines given by WAEC  to follow while writing the exams below.

Important Guidelines to follow in your WAEC Examination

There are alot of guidelines and instructions you as a student need to follow. We will bring to light what needs to be done accordingly.

The examination paper is divided into three different parts, which is Part 1, 2 & 3

Part 1 is Objectives. You should expect 50 questions from this section.

Part 2  is the theory section, you should be expecting 10 questions to answer 5 from this section. This section carries the highest point.

Meaning that if you do well with this section and a little of part 1 & 2…then you’re good to go.

Part 3 is the practical section where you perform an experiment of what you’ve been taught during lesson hours.

You should also note that the West African Examination Council frowns at cheating. Any candidate who is caught cheating will be sentenced to life imprisonment.

WAEC Chemistry Objective Questions

The questions you see below are possible questions that might be repeated in this year’s examination.

Endeavor to read this guide to the end carefully with understanding, where possible ask relevant questions and we’ll reply prompt.

SECTION A:

1. The periodic table is an arrangement of elements according to their

A. Oxidation number.
B. Atomic number.
C. Mass number.
D. Number of neutrons.

2. A solid substance with high melting and boiling points is likely to be

A. a covalent compound.
B. a dative covalent compound.
C. an electrovalent compound.
D. a non-metal.

3. Which of the following metals reacts slowly with cold water?

A. Iron
B. Silver
C. Calcium
D. Potassium

4. Which of the following elements has the highest ionization energy?

A. Calcium
B. Chlorine
C. Flourine
D. Magnesium

5. The bleaching action if chlorine is through the process of

A. Hydration
B. Hydrolysis
C. Reduction
D. Oxidation

6. Calcium and magnesium belong to the same group if the periodic table because both

A. are metals.
B. form cations.
C. form colourless salts
D. have same number of valence electrons

7. Which of the following pairs of components have the same molecular mass?
[H=1.0, C=12.0, O=16.0]

A. Ethene and ethyne
B. Ethane and ethene
C. Carbon (II) oxide and ethene
D. Carbon (IV) oxide and ethyne

8. When an equilibrium is established between dissolved and undissolved solutes, the solution is said to be

A. Saturated.
B. Unsaturated.
C. Concentrated.
D. Dilute.

9. How many moles of carbon (IV) oxide contains 16.0 g of oxygen?
[C=12.0, O=16.0]

A. 0.20 mol
B. 0.25 mol
C. 0.40 mol
D. 0.50 mol

10. Stoichiometry is based on the law of

A. multiple proportion.
B. constant composition.
C. conversation of energy.
D. conversation of mass.

11. 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.

12. What is the solubility of a salt X at 25 ºC if the saturated solution of the salt contains 0.28 g in 100 cm³ of solution?
[X= 56.0 g]

A. 0.05 mol dm¯³
B. 0.10 mol dm ¯³
C. 2.60 mol dm¯³
D. 2.80 mol dm¯³

13. In Boyle’s law,

A. T is constant, while P varies directly with V.
B. P is constant, while V varies inversely with T.
C. V is constant, while P varies directly with T.
D. T is constant, while V varies inversely with P.

14. Which of the following apparatus is not used in volumetric analysis?

A. Pipette
B. Burette
C. Desiccator
D. Conical flask

15. The method used to collect a gas in the laboratory depends on its

I. boiling point.
II. density.
III. smell.
IV. solubility in water.

A. I and II only.
B. II and IV only.
C. III and IV only.
D. I, II, III and IV.

WAEC Chemistry Theory Questions

Question 1
(i) What is an acid-base indicator?
(ii) Give one example of an acid-base indicator.
Define enthalpy of combustion.
(ii) State why the enthalpy of combustion is always negative.
(i) Distinguish between a primary cell and a secondary cell.
Define the term mole.

Calculate the amount of hydrochloric acid in 40.0 cm3 of 0.40 moldm-3 dilute HCl. [

Name two substances which can be used as electrodes during the electrolysis of acidified water.

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

Name the products formed when butane undergoes incomplete combustion.

Write the electron configuration of 26Fe3+.

Question 2

(i) I. State the periodic law
II. 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
(ii) varies across the period.

(i) State the method used for collecting each of the following gases:
I. CO2;
II. HCl;
III.H2

Question 3

(i) Describe briefly the industrial preparation of ammonia.
(ii) Write a balanced equation for the reaction in 4(a)(1).
(iii) State one way of increasing the yield of ammonia in 4(a)(i).
(iv) State two uses of ammonia.

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

(i) State the composition of water gas.
(ii) List two uses of water gas.

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

Question 4

(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).

(i) Write balanced equations for the reaction involved in the extraction of iron in the blast furnace.
(ii) State Faraday’s first law of electrolysis.
(iii) State two applications of electrolysis.

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

Write an equation for the reaction of zinc powder with:
(i) dilute tetraoxosulphate (VI) acid;
(ii) concentrated tetraoxosulphate (VI) acid.

What property of concentrated tetraoxosulphate (VI) acid is shown in 5(d)(ii)?

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