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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.

88 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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88 questions

Question 1 of 20 88 total questions

Question 21

jamb 1994

MnO4(aq) + 8H + 5Fe2+ \(\to\) Mn2+(aq) + 5Fe3+(aq) + H2O. The oxidation number of maganese in the above reaction changed from

A+7 to +2

B+6 to +2

C+5 to +2

D+4 to +2

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Question 22

jamb 1994

Use the diagram above to answer this question. The reaction taking place in flask G is known as?

Ahydrolysis

Bdouble decomposition

Cdehydration

Dpyrolysis

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Question 23

jamb 1994

The IUPAC name of the compound above is

A2,2-dimethyl but -1-yne

B2,2-dmethyl but -1-ene

C3,3-dimethyl but -1-ene

D3,3-dimethyl but-1-yne

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Question 24

jamb 1994

In the diagram above, R is a mixture of?

Apotassium tetraxochlorate (VII) and concentrated H₂SO₄

Bpotassium trioxochlorate (V) and concentrated H₂SO₄

Cpotassium tetratoxomanganate (VII) and concentrated HCI

Dmanganese (IV) oxide and concentrated HCI

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Question 25

jamb 1994

2HCL(ag) + CaCO3(ag) → CaCL2(ag) + H2O(1) + CO from the reaction above, which of the following curves represents the consumption of calcium trioxocarbonate (IV) as dilute HCL is added to it?

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Question 26

jamb 1994

In the diagram above the activation energy is represented by

Ay - x

Cx - z

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Question 27

jamb 1994

The ∆H for the reaction represented by the energy profile above is

A-100 kJ mol-^-1

B+ 100 kJ mol^-1

C+50 kJ mol^-1

D-50 kJ mol^-1

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Question 28

jamb 1994

The set-up above would be useful for determining the amount of

Aoxygen in air

Bwater vapour in air

CCO₂ in air

Darygen in air

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Question 29

jamb 1994

The diagram above represents an atom of

Amagnesium

Bhelium

Cchlorine

Dneon

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Question 30

jamb 1994

Which of the following reagents will confirm the presence of unsaturation in a compound?

AFehling's solution

BBromine water

CTollen's reagent

DBenedict's solution

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Question 31

jamb 1994

One mole of a hydrocarbon contains 48 g of carbon. If it vapour density is 28, the hydrocarbon is?

Aan alkane

Ban alkene

Can alkyne

Daromatic (C = 12, H = 1)

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Question 32

jamb 1994

The general formula of alkanoates is?

ARCHO

BR₂CO

CRCOOH

DRCOOR

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Question 33

jamb 1994

When sodium is added to ethanol, the products are?

Asodium hydroxide and water

Bsodium hydroxide and hydrogen

Csodium ethoxide and water

Dsodium ethoxide and hydrogen

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Question 34

jamb 1994

Which of the following compounds is NOT an isomers of 2,2 dimethylbutane?

A2-methylbutane

B3-methylpentane

C2,3-dimethylbutane

D2-methylpentane

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Question 35

jamb 1994

Which of the following is the correct order of decreasing activity of the metals Fe, Ca, Al and Na?

AFe> Ca> Al> Na

BNa> Ca> Al> Fe

CAl> Fe> Na> Ca

DCa> Na> Fe>, Al

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Question 36

jamb 1994

Which of the following is NOT true of metals?

AThey are good conductors of electricity

BThey ionize by electron loss

CTheir oxides are acidic

DThey have high melting points

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Question 37

jamb 1994

In an electrolytic set-up to protect iron from corrosion, the iron is?

Amade cathode

Bmade anode

Cused with a metal of lower electropositive potential

Dinitially coated with tin

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Question 38

jamb 1994

SO₃ is NOT directly dissolved in water in the preparation of H₂SO₄ by the contact process because?

Athe reaction between SO₃ and water is violently exothermic

Bacid is usually added to water and never water to acid

CSO₃ does not dissolve in water readily

DSO₃ is an acid gas

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Question 39

jamb 1994

Which of these solutions will give a white precipitate with a solution of barium chloride acidified with hydrochloric acid?

ASodium trioxocarbonate (IV)

BSodium tetraoxosulphate (IV)

CSodium trioxosulphate (IV)

DSodium sulphide

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Question 40

jamb 1994

Clothes should be properly rinsed with water after bleaching because?

Athe bleach decolourizes the cothes

Bchlorine reacts with fabrics during bleaching

Cthe clothes are sterilized during bleaching

Dhydrogen chloride solution is produced during bleaching

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