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Chemistry Past Questions

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168 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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168 questions

Question 1 of 20 168 total questions

Question 21

neco 2009

The following compounds decolorize acidified potassium tetraoxomanganate (VII) solution EXCEPT

AHOCH₂ – CH₂OH

BH₂C –C =C– CH₃

CH₃C – HC = CH₂

DH₂C = CH₂

EH₃C – C =CH

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Question 22

neco 2009

The percentage composition of a hydrocarbon is 79.2 carbon 20.8 hydrogen. Calculate its empirical formula [H = 1, C = 12]

ACH

BCH₃

CCH₄

DC₂H₂

EC₂H₆

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Question 23

neco 2009

Which of the following non-metals reacts most readily with metals?

ACarbon

BChlorine

CNitrogen

DPhosphorus

ESulphur

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Question 24

neco 2009

Compound with the general formula CnH\(_{2n+2}\) belong to the_______ group

Aalkanal

Balkane

Calkanoate

Dalkene

Ealkyne

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Question 25

neco 2009

The process involved in the decomposition of sugar by an enzyme is called

Adehydration

Besterification

Cfermentation

Dpolymerization

Esaponification

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Question 26

neco 2009

Which of the following equations is NOT balanced?

ACH₄(g) + 20₂(9) → CO₂(g) + 2H₂O(g)

BCU(S) + HNO₃(aq) → Cu(NO₃)₂(aq) + 4H₂O(I) + NO(g)

C2KCIO₃(s) → 2KCI(s)+ 3O₂(g)

DNaH(s) + H₂O(1) → NaOH(aq) +H₂(g)

ENa₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq)

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Question 27

neco 2009

A colourless gas with characteristics odour which dissolves in water to form an alkaline solution is

Aammonia

Bcarbon(IV)oxide

Chydrogen chloride

Dsulphur (IV) oxide

Esulphur (VI) oxide

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Question 28

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)

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Question 29

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

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Question 30

neco 2008

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

D10

E14

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Question 31

neco 2008

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

Aactivation energy

Benthalpy

Centropy

Dequilibrium

Efree energy.

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Question 32

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

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Question 33

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\( 0 \)

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Question 34

neco 2008

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

Adiffusion

Bmigration

Creaction

Dsedimentation

Esublimation.

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Question 35

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.

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Question 36

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

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Question 37

neco 2008

The following gases are diatomic EXCEPT

AFluorine

BHelium

CHydrogen

DNitrogen

EOxygen

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Question 38

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

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Question 39

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.

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Question 40

neco 2008

Brownian motion explains

ABoyle’s law

BCollision theory

CLaws of chemical combination

DMolecular motion in liquids and gases

EVibrational motion in liquids.

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