Chemistry Past Questions

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4,306 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10
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Past Questions

4,306 questions
Question 1 of 20 4,306 total questions
Question 461
waec 2018

Which of the following CANNOT be an empirical formula?

A\(CH\)
B\(CH_{2}\)
C\(P_{2}O_{5}\)
D\(N_{2}O_{4}\)
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Question 462
waec 2018

\(Cu\) and \(HNO_{3}\) are not suitable for preparing hydrogen gas because of their

Areactivity and oxidation respectively
Bconductivity and corrosiveness respectively
Cmelting point and reduction respectively
Delectronegativity and solubility respectively
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Question 463
waec 2018

Consider the following reaction equation: \(2HCl + Ca(OH)_{2} \to CaCl_{2} + H_{2}O\). What is the volume of 0.1\(moldm^{-3}\) HCl that would completely neutralize 25\(cm^{3}\) of 0.3\(moldm^{-3}\) Ca(OH)\(_{2}\)?

A150\(cm^{3}\)
B75\(cm^{3}\)
C30\(cm^{3}\)
D25\(cm^{3}\)
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Question 464
waec 2018

Which of the following statements best explains the difference between a gas and a vapour?

AUnlike gases, vapours are liquids at room temperature
BUnlike gases, vapour can easily be condensed into liquids
CUnlike gases, vapour is readily converted into solids
DVapours are generally denser than gases
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Question 465
waec 2018

The diagram above illustrates a conical flask containing water and ice. Which of the following is correct about the diagram?

AThe water is at lower temperature than the ice
BEnergy is absorbed when the ice changes to water
CEnergy is released when the ice changes to water
DThe water molecules vibrate about a fixed point
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Question 466
waec 2018

The position of equilibrium in a reversible reaction is affected by

Aparticle size of the reactants
Bvigorous stirring of the reaction mixture
Cpresence of a catalyst
Dchange in concentration of the reactants
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Question 467
waec 2018

The following factors would contribute to environmental pollution except

Aproduction of ammonia
Bmanufacture of cement
Cphotosynthesis
Dcombustion
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Question 468
waec 2018

The most suitable substance for putting out petrol fire is

Awater
Bcarbon(IV) oxide
Cfire blanket
Dsand
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Question 469
waec 2018

The number of Hydrogen ions in 1.0\(dm^{3}\) of 0.02\(moldm^{-3}\) tetraoxosulphate(VI) acid is   \([N_{A} = 6.02 \times 10^{23}]\)

A\(1.2 \times 10^{22}\)
B\(1.2 \times 10^{23}\)
C\(2.4 \times 10^{22}\)
D\(2.4 \times 10^{23}\)
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Question 470
waec 2018

Stainless steel is an alloy comprising of

AFe and C
BFe and Ni
CFe, C and Ni
DFe, C and Al
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Question 471
waec 2018

The valence electrons of \(_{12}Mg\) are in the

A3s orbital
B2p\(_{x}\)
C2s orbital
D1s orbital
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Question 472
waec 2018

The preferential discharge of ions during electrolysis is influenced by the 

Amechanism of electrolysis
Belectrolytic reactions
Cnature of the electrode
Dtype of electrolytic cell
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Question 473
waec 2018

When substance X was added to a solution of bromine water, the solution became colourless. X is likely to be

Apropane
Bpropanoic acid
Cpropyne
Dpropanol
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Question 474
waec 2018

When a salt is added to its saturated solution, the salt

Adissolves and the solution becomes super saturated
Bdissolves and the solution becomes unsaturated
Cprecipitates and the solution remains unchanged
Ddissolves and crystals are formed
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Question 475
waec 2018

At what temperature does the solubility of \(KNO_{3}\)  equal that of \(NaNO_{3}\)?   

A0°C
B20°C
C30°C
D40°C
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Question 476
waec 2018

Pure water can be made to boil at a temperature lower than 100°C by

Areducing its quantity
Bdecreasing the external pressure
Cdistilling it
Dincreasing the external pressure
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Question 477
waec 2018

What is the mass of solute in 500\(cm^{3}\) of 0.005\(moldm^{-3}\) \(H_{2}SO_{4}\)? ( H = 1, S = 32.0, O=16.0)

A0.490g
B0.049g
C0.245g
D0.0245g
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Question 478
waec 2018

Consider the following equilibrium reaction: \(2AB_{{2}{(g)}} + B_{{2}{(g)}} \to 2AB_{{3}{(g)}}\). \(\Delta H= -X kJmol^{-1}\). The backward reaction will be favored by

Aa decrease in pressure
Ban increase in pressure
Ca decrease in temperature
Dan introduction of a positive catalyst
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Question 479
waec 2018

Ethene is produced from ethanol by

Adecomposition
Bhydrolysis
Cozonolysis
Ddehydration
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Question 480
waec 2018

Consider the following reaction equation: \(Br_{2} + 2KI \to 2KBr + I_{2}\). Bromine is acting as

Aan oxidizing agent
Ba reducing agent
Can acid
Da base
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