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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.

87 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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87 questions

Question 1 of 20 87 total questions

Question 11

waec 1992

Consider the compounds represented by the following general formula: X₂SO₄ Y₂(SO₄)₃, 24H₂OX and Y could respectively be

AK and AI

BFe and K

CAI and Fe

DAI and K

ECr and K

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Question 12

waec 1992

When iron rusts, it undergoes

Adeliquescence

Bchemical decomposition

Chydrolysis

Dredox reaction

Ecombustion

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Question 13

waec 1992

What is the change in the oxidation number of phosphorus in the the reaction represented by the following equation? 4P _(s) + 5O₍₂₎_(g) → 2P₂O₅_(g)

A0 to + 2

B0 to 5

C+4 to + 2

D+4 to +5

E+4 to +7

View Explanation & Discuss

Question 14

waec 1992

What is the following compounds will not decompose when heated strongly ?

ANaHCO₃

BK₂CO₃

CMgCO₃

DCa(HCO₃)₂

EZnCO₃

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Question 15

waec 1992

''The rate a reaction is proportional to the number of effective collisions occurring per second between the reactants''. This statement is associated with the

AKinetic theory

Brate law

Catomic theory

Dcollision theory

Egas laws

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Question 16

waec 1992

What is the quantity of electricity produced when a current of 0.5A is passed for 5 hours 45 mins? (1F = 96500C)

A0. 11F

B0.12F

C0.22F

D1.1F

E2.2F

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Question 17

waec 1992

The scum formed when soap is mixed with hard water could be

Acalcium trioxocarbonate (IV)

Bpropane- 1, 2, 3 - triol

Ccalcium hydrogentrioxocarbonate (IV)

Dmagnesium tetraoxosulphate (IV)

Ecalcium stearate

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Question 18

waec 1992

The halide used widely in photography is

Aammonium chloride

Bcalcum chloride

Csilver bromide

Dsodium brmide

Ealuminium fluroide

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Question 19

waec 1992

When air is passed through potash and then pyrogallol, the components are noble gases,

Aoxygen and carbon (IV) oxide

Boxygen and nitrogen

Cnitrogen and water vapour

Dwater vapour and carbon (IV) oxide

Eoxygen and water vapour

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Question 20

waec 1992

The reactions ethyne are mainly

Asubstitution reactions

Baddition reactions

Caddition polymerization

Dcatalytic hydrogenation

Ecatalytic halogenation

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Question 21

waec 1992

The following acids are monobasic except

Amethanoic acid

Bdioxonitrate lll acid

Cethanedioic acid

Doxochlorate (l) acid

Ehydrobromic acid

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Question 22

waec 1992

If the volume of a given mass of gas at 298 K and pressure of 205.2 x 10\(^3\) Nm\(^{-2}\) is 2.12dm\(^3\), what is volume of the gas at s.t.p? (Standard pressure = 101.3 x 10\(^3\) Nm\(^{-2}\), Standard temperature = 273K)

A39.3dm ³

B22.4dm³

C4.93dm³

D3.93dm³

E0.393dm³

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Question 23

waec 1992

Which of the following processes is a physical reaction?

AElectrolysis

BHydrolysis

CAllotropic change

DNeutralization

ECorrosion

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Question 24

waec 1992

Study carefully the reaction represented by the equation below. 2H2O 2(l) → O 2(g) + 2H2O(l). Which of the following will not reaction increase the reaction rate?

AHeating the hydrogen peroxide

BAdding a pinch of MnO₂ to the reactant

Cincreasing the concentration of the H₂O₂

DAdding water to the reactant

EExposing the reactant to sunlight

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Question 25

waec 1992

Methanol is obtained from wood by

Aesterification

Bbacterial decomposition

Ccombustion

Dfractional distillation

Edestructive distillation

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Question 26

waec 1992

The maximum number of electrons that can accommodated in the shell having the principal quantum number 3 is

C10

D18

E32

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Question 27

waec 1992

When steam is passed over white-hot coke, the products are

Acarbon (IV) oxide and nitrogen

Bcarbon (II) oxide and hydrogen

Ccarbon (ll) oxide and nitrogen

Dcarbon (lV) oxide and steam

View Explanation & Discuss

Question 28

jamb 1992

The nucleus of the isotopes tritium,contains

Atwo neutrons with no protons

Bone neutron and one proton

Ctwo neutrons and one proton

Dtwo neutrons, one proton and one electron

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Question 29

jamb 1992

A given mass of gas occupies 2 dm² at 300k. At what temperature will its volume be doubled keeping the pressure constant?

A400k

B480k

C550k

D600k

View Explanation & Discuss

Question 30

jamb 1992

Which of the following compounds is a secondary alkanol?

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