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.

50 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10
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Past Questions

50 questions
Question 1 of 20 50 total questions
Question 11
jamb 2001

Fermentation is the

Abreaking down of carbohydrate to glucose
Bconversion of sugar to alcohol in the presence of yeast
Cbreaking down of sugar to carbohydrate
Dconversion of alcohol to sugar in the presence of yeast
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Question 12
jamb 2001

NH\(_3\)\(_{(g)}\) + HCl\(_{(g)}\) → NH\(_4\)Cl\(_{(s)}\)
The entropy change in the system above is

Anegative
Bindeterminate
Cpositive
Dzero
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Question 13
jamb 2001

In which of the following reactions has the oxidation number of nitrogen increased?

A2NO(g) + Br2(l) → 2NOBr(l)
B2NO(g) + O2(g) → 2NO2(g)
CFeSO4(aq) + NO(g) → Fe(NO)SO4(s)
D2NO(g) + Cl2(g) → 2NOCl(l)
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Question 14
jamb 2001

As the concentration of an electrolyte reduces, the conductivity

Areduces to zero
Bdecreases
Cincreases
Dis unaffected
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Question 15
jamb 2001

When ΔH is negative, a reaction is said to be

Aionic
Breversible
Cexothermic
Dendothermic
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Question 16
jamb 2001

3Cu(s) + 8HNO\(_3\)(aq)  → 3Cu(NO\(_3\))\(_2\)(aq) + 4H\(_2\)O(l) + 2NO(g)
In the equation above, copper is

Aan electron acceptor
Ba base
Can oxidizing agent
Da reducing agent
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Question 17
jamb 2001

2SO\(_2\)(g) + O\(_2\)(g) ↔ 2SO\(_3\)(g)
ΔH = -189 kJ mol-1
The equilibrium constant for the reaction above is increased by?

Adecreasing the temperature of the system
Bdecrease the pressure of the system
CThe addition of a catalyst to the system
DIncreasing the surface area of the vessel
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Question 18
jamb 2001

C(s) + 2S(g) → CS\(_2\)(g)
ΔH = +89 kJ mol-1
The chemical equation above implies that

Aeach of carbon and sulphur has 89 kJ of energy
Bboth carbon and sulphur contribute 89 kJ of energy
C89 kJ of energy is released
D89 kJ of energy is absorbed
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Question 19
jamb 2001

Ethanoic acid is

Atribasic
Bunionizeable
Cmonobasic
Ddibasic
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Question 20
jamb 2001

What current in amperes will deposit 2.7g of aluminium in 2 hours?
[Al = 27, F = 96 500 C mol-1]

A32
B8
C4
D16
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Question 21
jamb 2001

Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises?

AThe bonds in the reacting molecules are more readily broken
BThe molecular collisions become more violent
CA lower proportion of the molecules has the necessary minimum energy to react
DThe collision frequency of the molecules increase
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Question 22
jamb 2001

A metal M displaces zinc from zinc chloride solution. This shows that

AM is more electronegative than zinc
BZinc is above hydrogen in the series
CM is more electropositive than zinc
DElectrons flow from zinc to M
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Question 23
jamb 2001

P(g) + Q(g) ↔ 3R(s) + S(g) ΔH is negative
Which of the following will increase the yield of R?

AUsing a larger close vessel
BIncreasing the temperature
CRemoving some S
DAdding a positive catalyst
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Question 24
jamb 2001

In which of the following reactions does reduction takes place

AFe2+ - e- → Fe3+
B2O2- →O2 + 4e-
CCr – 2e- → Cr2+
D2H+ + 2e- → H2
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Question 25
jamb 2001

Phosphorus is stored under water to prevent it from

ADehydrating
BBecoming inert
CSmelling
DCatching fire
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Question 26
jamb 2001

The chemical used for coagulation in water purification is

AAluminium tetraoxosulphate (VI)
BCopper tetraoxosulphate (VI)
CSodium tetraoxosulphate (VI)
DCalcium tetraoxosulphate (VI)
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Question 27
jamb 2001

Environmental pollution is worsened by the release from automobile exhausts of?

AWater vapour
BSteam
CSmoke
DHeavy metals
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Question 28
jamb 2001

What is the decrease in volume of air when pyrogallol is shaken with 30.00cm\(^3\) of air ?

A15.00cm3
B6.30cm3
C0.63cm3
D0.06cm3
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Question 29
jamb 2001

Pure solvents are obtained by

ADistillation
BCondensation
CExtraction
DEvaporation
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Question 30
jamb 2001

Deliquescent substances are used for

ACooling
BWetting
CMelting
DDrying
View Explanation & Discuss
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