Classroom

Chemistry Past Questions

Study and practice Chemistry past questions with answers and detailed explanations. Then test your knowledge using our interactive CBT practice platform and prepare confidently for your upcoming examinations.

2,505 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

Select subject

Download PHP app Ask a Question Check Syllabus Past Question Videos Topic Video Lessons

Take a test

Custom CBT

Create and set up a CBT environment with your preferred subjects.

JAMB CBT Simulator

Practice JAMB CBT with real UTME past questions in CBT format.

WAEC CBT Practice 2026 Simulator

CB-WASSCE styled past question practice.

NECO CBT Practice 2026 Simulator

SSCE & GCE styled past question practice.

Past Questions

2,505 questions

Question 1 of 20 2,505 total questions

Question 971

jamb 1990

Fe\(_2\)O\(_{3(s)}\) + 2Al\(_{(s)}\) → Al\(_2\)O\(_3\) + 2Fe\(_{(s)}\). If the heats of formation of Al\(_2\)O\(_3\) and Fe\(_2\)O\(_3\) are - 1670 kJmol\(^{-1}\) and - 822 kJmol\(^{-1}\) respectively, the enthalpy change in kJ for the reaction is ?

A+2492

B+848

C-848

D-2492

View Explanation & Discuss

Question 972

jamb 1990

In the reaction 1O^-₃ + 5l^- + 6H⁺ → 31₂ + 3H₂O, the oxidizing agent is?

AH⁺

Bl^-

C1O^-

Dl₂

View Explanation & Discuss

Question 973

jamb 1990

Cr\(_2\)O\(_7\)\(^{2-}\) + 6Fe\(^{2+}\) + 14H\(^+\) → 2Cr\(^{3+}\) +6Fe\(^{3+}\) + 7H\(_2\)O. In the above , the oxidation number of chromium changed from?

A+7 to +3

B+6 to +3

C+5 to +3

D-2 to +3

View Explanation & Discuss

Question 974

jamb 1990

In a reaction: \(SnO_{2} + 2C → Sn + 2CO\) the mass of coke containing 80% carbon required to reduce 0.302 kg of pure tin oxide is?
(Sn - 119, O - 16, C - 12).

A0.40 kg

B0.20 kg

C0.06 kg

D0.04 kg

View Explanation & Discuss

Question 975

jamb 1990

Which of the following is a physical change?

AThe bubbling of chlorine into water

BThe bubbling of chlorine into a jar contanining hydrogen

CThe dissolution of sodium chloride in water

DThe passing of steam over heated iron

View Explanation & Discuss

Question 976

jamb 1989

CO(g) + H\(_2\)O(g) \(\to\) \(CO_{2g}\) + H\(_2\)(g) \(\Delta\)H = - 4100J. Which of the following factors favour the formation of hydrogen in the above reaction? i. high pressure. ii. low pressure iii. high-temperature iv. use of excess steam

Ai, iii and iv

Biii only

Cii, iii and i

Div only

View Explanation & Discuss

Question 977

jamb 1989

What is the IUPAC name for the compound

A1-chloro-2-methylprop-2,3-ene

B1-chloro-2-methylprop-2-ene

C3-chloro-2-methylprop-1-ene

D3-chloro-2methylprop-1,2-ene

View Explanation & Discuss

Question 978

jamb 1989

Use the figure above to answer this question. Which of the following is NOT an isomer of the compound?

View Explanation & Discuss

Question 979

jamb 1989

Use the figure above to answer this question. Which of the following compounds is an isomer of the compound

View Explanation & Discuss

Question 980

jamb 1989

The above graph shows a typical heating curve from the solid phase through the liquid phase to the gaseous phase of a substance. Which part of the curve shows solid and liquid in equilibrium?

View Explanation & Discuss

Question 981

jamb 1989

If in the graph above 1 dm 3 of a saturated solution of KCL is cooled from 80°C, the mass of crystals deposited will be
[K = 39, Cl = 35.5]

A7.45 g

B14.90 g

C74.50 g

D149.00 g

View Explanation & Discuss

Question 982

jamb 1989

The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X(g) + Y(g) → XY(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X(g) + Y(g)

A300, 500

B500, 300

C-300, -500

D-500, -300

View Explanation & Discuss

Question 983

jamb 1989

Which of the curves in the above graph illustrates the behaviour of an ideal gas?

View Explanation & Discuss

Question 984

jamb 1989

In the above set up substances X and Y are respectively

Alime water copper (ll) tetraoxosulphate (lV)

Bpotassium trioxocarbonate and alkaline pyrogallol

Cpotassium hydroxide and alkaline pyrogallol

Dpotassium trioxocarbonate (lV) and concentrated tetraoxosulphate (IV) acid

View Explanation & Discuss

Question 985

jamb 1989

It can be deduced from the vapour pressure curves above that

Aliqiud 1 has the highest boiling point

Bliquid ll has the highest boiling point

Cliquid lll has the highest boiling point

Dliquid lll has the lowest boiling point

View Explanation & Discuss

Question 986

jamb 1989

Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature?

AX and Z

View Explanation & Discuss

Question 987

jamb 1989

The gas responsible for most of the fatal explosions in coal mines is

Abutane

Bethene

Cethane

Dmethane

View Explanation & Discuss

Question 988

jamb 1989

The alkaline hydrolysis of fats and oils produces soap and

Apropane 1, 1, 3 - triol

Bpropane - 1,2,3 - triol

Cpropane - 1,3,3 - triol

Dpropane - 1, 2, 2 - triol

View Explanation & Discuss

Question 989

jamb 1989

The bond which joins two ethanoic acid molecules in the liquid state is

Aa covalent bond

Ban ionic bond

Ca dative covalent bond

Da hydrogen bond

View Explanation & Discuss

Question 990

jamb 1989

The reaction between ethanoic acid and sodium hydroxide is an example of

Aesterification

Bneutralization

Chydroxylation

Dhydrolysis

View Explanation & Discuss

Question Navigator

Current

Chemistry Past Questions

Take a test

Custom CBT

JAMB CBT Simulator

WAEC CBT Practice 2026 Simulator

NECO CBT Practice 2026 Simulator

Past Questions

Question Navigator

MathsFaculty