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.

42 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

42 questions

Question 1 of 20 42 total questions

Question 1

neco 2008

In which of the following equations can Le-chartelier’s principle be applied?

AH₂(g)+S(g) → H₂(g)

B2H₂S(g) + O₂ (g) → 2H2O(l) + 2SO₂(g)

CN₂(g) +3H₂(g) ⇌ 2NH₃(g)

DNaOH(aq) +CO₂(g) → Na₂CO₃(aq) + H₂O(l)

ES(s) + 0₂(g) → SO₂(g)

View Explanation & Discuss

Question 2

neco 2008

In which of these groups will all the substances be insoluble in water?

ANa₂CO₃, KNO₃,(NH₄)₂C0₃

BNaHCO₃, PbSO₄, CaSO₄

CK₂C0₃, CaSO₄, AgNO₃

DPbCl₂, NaCl, ZnCl₂

EZnCO₃, BaSO₄,AgCl

View Explanation & Discuss

Question 3

neco 2008

What is the maximum number of electrons that an f-orbital can accommodate?

D10

E14

View Explanation & Discuss

Question 4

neco 2008

A measure of the degree of disorderliness in a chemical system is known as the

Aactivation energy

Benthalpy

Centropy

Dequilibrium

Efree energy.

View Explanation & Discuss

Question 5

neco 2008

A substance is said to be hygroscopic when it

Aabsorbs atmospheric moisture and then goes into solution

Babsorbs atmospheric moisture but does not go into solution

Cchanges colour

Dis not affected by atmospheric moisture

Elosses its water of crystallization

View Explanation & Discuss

Question 6

neco 2008

The electrode potential in volts of 2H\(^+\)(aq) / H\(_2\)(q) system is

A-2.87

B-2.71

C0.8

D1.68

E\( 0 \)

View Explanation & Discuss

Question 7

neco 2008

Chromatography is used to separate components of mixtures which differ in their rates of

Adiffusion

Bmigration

Creaction

Dsedimentation

Esublimation.

View Explanation & Discuss

Question 8

neco 2008

During the electrolysis of sodium Chloride solution, hydrogen is discharged at the carbon cathode because

Ahydrogen ions are in greater concentration than sodium ions.

Bhydrogen is higher than sodium in the electrochemical series.

Chydrogen is lower than sodium in the electrochemical series.

Dof the nature of the electrodes.

Ethe concentration of sodium ions is greater than that of the hydrogen ion in the electrolyte.

View Explanation & Discuss

Question 9

neco 2008

Which of these is NOT a physical property f water?

ACan be used to dissolve organic substances

BHas a boiling point of 100 ° C

CHas a density of 19cm3 at 40 °C

DHas a freezing point of 0 ° C

Eis neutral to litmus

View Explanation & Discuss

Question 10

neco 2008

The following gases are diatomic EXCEPT

AFluorine

BHelium

CHydrogen

DNitrogen

EOxygen

View Explanation & Discuss

Question 11

neco 2008

If two elements X and Z with electronic configurations 2,8.3 and2,8,6 respectively combine, the compound formed will have the formula

AXZ

BXZ₂

CX₂Z

DX₂Z₃

EX₃Z₂

View Explanation & Discuss

Question 12

neco 2008

The reaction of hydrochloric acid and calcium trioxocarbonate (IV) produces

Acalcium chloride, carbon (IV) oxide and water

Bcalcium chloride, and trioxocarbonate (IV) acid

Ccalcium hydroxide, carbon (IV) oxide and chlorine gas

Dcalcium hydroxide, carbon (IV) oxide and water

Ecalcium metal and water.

View Explanation & Discuss

Question 13

neco 2008

Brownian motion explains

ABoyle’s law

BCollision theory

CLaws of chemical combination

DMolecular motion in liquids and gases

EVibrational motion in liquids.

View Explanation & Discuss

Question 14

neco 2008

A chemical system is at equilibrium when

Aδ G is positive

Bδ G is zero

Cδ S is negative

Dδ S is positive

Eδ S is zero.

View Explanation & Discuss

Question 15

neco 2008

When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate formed re-dissolve in excess sodium hydroxide because

Asodium hydroxide is a strong alkali

Bsodium is more reactive than zinc

Czinc is more reactive than sodium

Dzinc hydroxide is amphoteric

Ezinc hydroxide is unstable

View Explanation & Discuss

Question 16

neco 2008

The gas in air used by plants for photosynthesis is

AArgon

BCarbon (IV) oxide

CNitrogen

DOxygen

EWater vapour.

View Explanation & Discuss

Question 17

neco 2008

Which of these arrangement of elements is in order of increasing ionization energy?

ABoron, Carbon, Flourine, Nitrogen

BBoron, Carbon, Nitrogen, Flourine

CCarbon, Boron, Nitrogen, Flourine

DFlourine, Nitro9en, Carbon, Boron

ENitrogen, Flourine, Carbon, Boron

View Explanation & Discuss

Question 18

neco 2008

The following acids are monobasic EXCEPT

Adioxonitrate (Ill) acid

Bethanedioic acid

Chydrobromic acid

Dmethanoic acid

Eoxochlorate (I) acid

View Explanation & Discuss

Question 19

neco 2008

An element Z has a combining power of 3. Which of the following formulae is correct of its compound?

AZS₃

BZSO₃

CZS0₄

DZ₂0₃

EZ₃Cl₂

View Explanation & Discuss

Question 20

neco 2008

Bauxite is the ore of

Aaluminium

Bcalcium

CIron

Dsodium

Emagnesium

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