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Chemistry Past Questions

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2,505 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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2,505 questions

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Question 231

jamb 2019

Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below?
2HCl + CaCO\(_3\) → CaCl\(_2\) + H\(_2\)O + CO\(_2\)

AIncreasing the concentration of the acid

BIncreasing the surface area of CaCO\(_3\)

CA and B

DReducing the concentration of the acid

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Question 232

jamb 2019

The part of the total energy of a system that accounts for the useful work done in a system is known as

AEnthalpy change

BNone of the above

CGibb's free energy

DEntropy

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Question 233

jamb 2019

When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is

Apropylmethanoate

Bethylpropanoate

Cmethyl ethanoate

Dmethyl propanoate

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Question 234

jamb 2019

An element Z contains 80% of \(^{16} _8\)Z and 20% of \(^{18} _8\)Z. Its relative atomic mass is

A16.2

B17.6

C16.0

D16.4

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Question 235

jamb 2019

How many electrons will be found in the nucleus of an atom with mass number 23 and 17 neutrons?

Anone

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Question 236

jamb 2019

A solution X, on mixing with AgNO\(_3\) solution gives a white precipitate soluble in aqueous NH\(_3\), a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

AAl\(^{3+}\), Cl\(^-\)

BHg\(^+\), SO\(_4 ^{2-}\)

CPb\(^{2+}\), Cl\(^-\)

DAg\(^+\), SO\(_4 ^{2-}\)

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Question 237

jamb 2019

The reaction \(2H_2 S + SO_2 \to 3S + 2H_2 O\) is

Anot a redox reaction because there is no oxidant in the reaction

Bnot a redox reaction because there is no reductant in the reaction

Ca redox reaction in which H\(_2\)S is the oxidant and SO\(_2\) is the reductant

Da redox reaction in which SO\(_2\) is the oxidant and H\(_2\)S is the reductant

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Question 238

jamb 2019

How many alkoxyalkanes can be obtained from the molecular formula C\(_4\)H\(_{10}\)O?

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Question 239

jamb 2019

The cost of discharging 6.0g of a divalent metal, X from its salt is ₦12.00. What is the cost of discharging 9.0g of a trivalent metal, Y from its salt under the same condition?
[X = 63, Y = 27, 1F = 96,500C]

AN12.00

BN27.00

CN63.00

DN95.00

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Question 240

jamb 2019

If the cost of electricity required to discharge 10g of an ion X\(^{3+}\) is N20.00, how much would it cost to discharge 6g of ion Y\(^{2+}\)?

[1 faraday = 96,500C, atomic masses are X = 27, Y = 24]

AN10.00

BN6.00

CN20.00

DN9.00

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Question 241

jamb 2019

Hydrogen diffused through a porous plug

Athrice as fast as oxygen

Bat the same speed as oxygen

Cfour times as fast as oxygen

Dtwice as fast as oxygen

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Question 242

jamb 2019

The emission of two successive beta particles from the nucleus \(^{32} _{15} P\) will produce

A\(^{30} _{14}\)Si

B\(^{32} _{13}\)Al

C\(^{32} _{17}\)Cl

D\(^{32} _{16}\)S

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Question 243

jamb 2019

The velocity, V of a gas is related to its mass, M by (k = proportionality constant)

AV = \(\frac{k}{M}\)

BV = \(\frac{k}{M^{\frac{1}{2}}}\)

CV = \(kM^2\)

DV = \((\frac{k}{M})^{\frac{1}{2}}\)

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Question 244

jamb 2019

X is a substance which liberates CO\(_2\) on treatment with concentrated H\(_2\)SO\(_4\). A warm solution of X can decolorize acidified KMnO\(_4\). X is

AHCOOH

BNaHCO\(_3\)

CFeCO\(_3\)

DH\(_2\)C\(_2\)O\(_4\)

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Question 245

jamb 2019

Which of the following conditions will most enhance the spontaneity of a reaction?

A\(\Delta\)H is negative and greater than T\(\Delta\)S

B\(\Delta\)H is negative and \(\Delta\)S = 0

C\(\Delta\)H is positive and less than T\(\Delta\)S

D\(\Delta\)H is positive and equal to T\(\Delta\)S

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Question 246

jamb 2019

200cm\(^3\) of 0.50mol/dm\(^3\) solution of calcium hydrogen trioxocarbonate (IV) is heated. The maximum weight of solid precipitated is

A10g

B25g

C20g

D15g

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Question 247

jamb 2019

Which of the following sets of operation will completely separate a mixture of sodium chloride, sand and iodine?

Aaddition of water, filtration, evaporation to dryness and sublimation

Bfiltration, evaporation to dryness, addition of water and sublimation

Csublimation, filtration, evaporation and addition of water

Dsublimation, addition of water, filtration and evaporation to dryness

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Question 248

jamb 2019

Methane is prepared in the laboratory by heating a mixture of sodium ethanoate with soda lime. The chemical constituent(s) of soda lime is/are

ACa(OH)\(_2\) and NaOH

BNa\(_2\)CO\(_3\)

CNaCl

DNaOH

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Question 249

jamb 2019

Hydrogen bond is a sort of

Avan der waals force

Bdative bond

Cionic bond

Da covalent bond

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Question 250

jamb 2019

The oxidation state(s) of nitrogen in ammonium nitrite is/are

A-3, +3

B+5

C-3, +5

D-3

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