Exam Body

Year

Subject

Paper Type

WAEC 2023 Chemistry | Objective

Prepare for your exams with WAEC questions? Reviewing past/model questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2023 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1 View Details

Which of the following laws or theory cannot be explained by the application of the kinetic theory of gases?

Correct A. Dalton's atomic theory

B. Charles' law

C. Gay-lussac's law

D. Boyle's law

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 2 View Details

The primary component of natural gas is

A. butane

B. ethane

Correct C. methane

D. propane

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 3 View Details

Thermal cracking of alkanes usually

Correct A. involves decomposition

B. is an exothermic process

C. produces only small alkanes

D. requires hydrogen

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 4 View Details

Carbon is deposited in the exhaust pipes of cars because of

A. contamination of petrol with diesel

B. presence of carbon in petrol

C. presence of additives in petrol

Correct D. incomplete combustion of petrol

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 5 View Details

How many moles of copper would be deposited by passing 1 Faraday of electricity through a \( \mathrm{CuCl}_{2} \) solution?

A. 2

Correct B. 1

C. 0.5

D. 0.25

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 6 View Details

Alkenes can be manufactured by

A. addition of hydrogen to unsaturated vegetable oils

Correct B. the cracking of hydrocarbons

C. polymerization reactions

D. the combustion of alkanes

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 7 View Details

Petrochemistry is an example of

A. pure chemistry

Correct B. applied chemistry

C. biochemistry

D. environmental chemistry

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 8 View Details

Species that occur in a reaction pathway but not in the overall reaction are known as

A. products

B. inhibitors

C. reactants

Correct D. intermediates

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 9 View Details

Which of the following statements is correct?

A. An alkane with 49 carbon atoms contains 100 hydrogen atoms

B. Addition reactions occur between alkanes and chlorine

C. Butane has a lower boiling point than propane

Correct D. Pentane has five isomers

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 10 View Details

The best indicator to use for the titration of ethanoic acid with sodium hydroxide is

A. methyl red

B. methyl orange

Correct C. phenolphthalein

D. screened methyl orange

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 11 View Details

The reduction half equation of the following reaction is:\[ \mathrm{Zn}_{(s)}+\mathrm{CuSO}_{4(aq)} \rightarrow \mathrm{ZnSO}_{4(aq)}+\mathrm{Cu}_{(s)} \]

A. \( \mathrm{CuSO}_{4(s)}+\mathrm{H}_{2}\mathrm{O}_{(l)} \rightarrow \mathrm{C}_{(aq)}^{2+}+\mathrm{SO}_{(aq)}^{2-} \)

B. \( \mathrm{Cu}_{(aq)}^{2+}+2 \mathrm{e} \rightarrow \mathrm{Cu}_{(s)} \)

Correct C. \( \mathrm{Cu}_{(aq)}^{2+}+\mathrm{e} \rightarrow \mathrm{Cu}_{(s)} \)

D. \( \mathrm{Zn}_{(s)} \rightarrow \mathrm{Zn}_{(aq)}^{2+}+2 \mathrm{e} \)

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 12 View Details

If \( 100 cm^{3} \) of a saturated solution of sodium tetraoxosulphate (VI) at \( 30^{\circ}C \) contains 10.5 g of the salt, what would be its solubility at this temperature? \( [\mathrm{Na}_{2}\mathrm{SO}_{4}=142] \)

A. 0.57 mol \( dm^{-3} \)

Correct B. 0.60 mol \( dm^{-3} \)

C. 0.74 mol \( dm^{-3} \)

D. 2.15 mol \( dm^{-3} \)

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 13 View Details

An example of a crystalline substance that does not possess water of crystallization is

Correct A. potassium trioxonitrate (V)

B. sodium trioxocarbonate (IV)

C. iron (II) tetraoxosulphate (VI)

D. sodium tetraoxosulphate (VI)

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 14 View Details

The salt solution formed from a reaction between ethanoic acid and sodium hydroxide solution would be

A. basic

B. acidic

Correct C. neutral

D. amphoteric

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 15 View Details

Which of the following reactions represents the hydrolysis of an alkanoate?

A. \( \mathrm{CH}_{3}\mathrm{COOH} + \mathrm{C}_{2}\mathrm{H}_{5}\mathrm{OH} \stackrel{H^{+}}{\rightleftharpoons} \mathrm{CH}_{3}\mathrm{COOC}_{2}\mathrm{H}_{5} + \mathrm{H}_{2}\mathrm{O} \)

Correct B. \( \mathrm{CH}_{3}\mathrm{COOC}_{2}\mathrm{H}_{5} + \mathrm{H}_{2}\mathrm{O} \xrightarrow{H^{+}} \mathrm{CH}_{3}\mathrm{COO}^{-} + \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH} \)

C. \( \mathrm{CH}_{3}\mathrm{COOCH}_{2}\mathrm{CH}_{3}\mathrm{CH}_{3} + \mathrm{H}_{2}\mathrm{O} \rightleftharpoons \mathrm{CH}_{3}\mathrm{COOH} + \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH} \)

D. \( \mathrm{CH}_{3}\mathrm{COOH} + \mathrm{OH}^{-} \stackrel{H^{+}}{\rightleftharpoons} \mathrm{CH}_{3}\mathrm{COO}^{-} + \mathrm{H}_{2}\mathrm{O} \)

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 16 View Details

Which of the following statements about the collision theory is correct?

A. All collisions bring about reactions

Correct B. Rate of reaction is proportional to the number of effective collisions

C. Collision of molecules will split the molecules to react

D. Ineffective collision brings about chemical reaction

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 17 View Details

Why are \( \mathrm{H}_{2}\mathrm{SO}_{4} \) and \( \mathrm{CaCl}_{2} \) not suitable for drying ammonia gas? They

A. are corrosive

B. are poisonous

Correct C. react with the gas

D. pollute the gas

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 18 View Details

Which of the following equations does not illustrate correctly one of the reactions of chlorine?

A. \( \mathrm{H}_{2}\mathrm{S} + \mathrm{Cl}_{2} \rightarrow 2 \mathrm{HCl} + \mathrm{S} \)

B. \( \mathrm{Cl}_{2} + 2 \mathrm{NaOH} \rightarrow \mathrm{NaCl} + \mathrm{NaClO} + \mathrm{H}_{2}\mathrm{O} \)

Correct C. \( \mathrm{Cl}_{2} + 2 \mathrm{NaF} \rightarrow 2 \mathrm{NaCl} + \mathrm{F}_{2} \)

D. \( \mathrm{Ca} (\mathrm{OH})_{2} + \mathrm{Cl}_{2} \rightarrow \mathrm{CaOCl}_{2} + \mathrm{H}_{2}\mathrm{O} \)

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 19 View Details

How many unpaired electrons are present in \( { }_{26} \mathrm{Fe}^{3+} \)

A. 2

Correct B. 3

C. 4

D. 5

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 20 View Details

Going down group II in the periodic table normally

A. shielding effect decreases

B. melting point increases

C. ionization energy increases

Correct D. electronegativity increases

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 21 View Details

Which of the following elements has its valence electrons in the s-orbital?

Correct A. Sodium

B. Carbon

C. Phosphorus

D. Aluminium

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 22 View Details

The periodic property that is used to determine whether a covalent molecule is polar or not is

A. atomic radius

B. electron affinity

Correct C. electronegativity

D. ionization energy

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 23 View Details

The following steps are scientific methods except

A. analysis

Correct B. open-mindedness

C. experimentation

D. problem identification

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 24 View Details

Isoelectronic species have the same number of

Correct A. electrons

B. neutrons

C. protons

D. ions

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 25 View Details

An element X has two isotopes, \( { }_{30}^{65} X \) and \( { }_{30}^{66} X \) with relative abundance of 60% and 40% respectively. The relative atomic mass of X is

A. 65.00

Correct B. 65.40

C. 65.50

D. 66.00

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows

Help others prepare! Share this practice hub:

Chat with Support