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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.

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

135 questions
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Question 1 of 20 135 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)
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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
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Question 3
neco 2008
What is the maximum number of electrons that an f-orbital can accommodate?
A2
B6
C7
D10
E14
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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.
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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
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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\( 0 \)
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Question 7
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 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.
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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
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Question 10
neco 2008
The following gases are diatomic EXCEPT
AFluorine
BHelium
CHydrogen
DNitrogen
EOxygen
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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.
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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.
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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.
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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
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Question 16
neco 2008
The gas in air used by plants for photosynthesis is
AArgon
BCarbon (IV) oxide
CNitrogen
DOxygen
EWater vapour.
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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
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Question 18
neco 2008
The following acids are monobasic EXCEPT
Adioxonitrate (Ill) acid
Bethanedioic acid
Chydrobromic acid
Dmethanoic acid
Eoxochlorate (I) acid
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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
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Question 20
neco 2008
Bauxite is the ore of
Aaluminium
Bcalcium
CIron
Dsodium
Emagnesium
View Explanation & Discuss
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