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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.

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

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2,505 questions

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Question 701

jamb 2002

The solubility of a salt of molar mass 101g at 20^oC is 0.34 mol dm^-3. If 3.40g of the salt is dissolved completely in 250cm³ of water in a beaker, the resulting solution is

AA suspension

BSaturated

CUnsaturated

DSupersaturated

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Question 702

jamb 2002

The product of the electrolysis of dilute sodium hydroxide using platinum electrodes are

AHydrogen and oxygen gases

BWater and hydrogen gas

CWater and sodium metal

DSodium metal and oxygen gas

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Question 703

jamb 2002

Cu\(_2\)S(s) + O\(_2\)(g) → 2CU(s) + SO\(_2\)(g)
What is the change in the oxidation number of copper in the reaction above?

A+1 to 0

B0 to +2

C+2 to +1

D0 to +1

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Question 704

jamb 2002

When dissolved in water, NaOH flakes show

AAn endothermic change

BAn exothermic change

CA slow reaction

DA rapid reaction

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Question 705

jamb 2002

The Arrhenius equation expresses the relationship between the speed of a reaction and its

AMolecular collision

BHeat of reaction

CCatalyst

DActivation energy

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Question 706

jamb 2002

When H\(_2\)S is passed into a solution of iron (III) chloride, the solution turns

APale green

BPale red

CBrown

DColourless

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Question 707

jamb 2002

PCl5(g) ↔ PCl3(g) + Cl2(g)
In the reaction above, a decrease in pressure will

ADecelerate the reaction

BIncrease the yield of PCl₃

CIncrease the yield of PCl₅

DAccelerate the reaction

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Question 708

jamb 2002

Which of the following equations show that a reaction is in equilibrium?

AΔG < O

BΔG = ΔH – TΔS

CΔG > O

DΔG = O

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Question 709

jamb 2002

What amount of mercury would be liberated if the same quantity of electricity that liberates 0.65g of zinc is applied?

A2.01g

B1.00g

C4.02g

D8.04g

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Question 710

jamb 2002

In the reaction E+F ↔ G+H, the backward reaction is favoured if the concentration of

AF is increased

BE is increased

CE is reduced

DG is reduced

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Question 711

jamb 2002

The chromatography separation of ink is based on the ability of the components to

AReact with solvent

BReact with each other

CDissolve in each other in the column

DMove at different speeds in the column

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Question 712

jamb 2002

A little quantity of trichloromethane (b.pt 60\(^0\)C) was added to a large quantity of ethanol (b.pt 78\(^0\)C). The most probable boiling point of the resultant mixture is from

A69 ^oC - 70 ^oC

B70 ^oC – 74 ^oC

C82 ^oC – 84 ^oC

D60 ^oC – 78 ^oC

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Question 713

jamb 2002

The formula CH\(_2\)O for ethanoic acid is regarded as its

AMolecular formula

BGeneral formula

CEmpirical formula

DStructural formula

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Question 714

jamb 2002

A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?
[K = 39, Cl = 35.5, O = 16]

AKClO₄

BKClO

CKClO₂

DKClO₃

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Question 715

jamb 2001

Use the solubility curves below to answer the question. If 1 dm\(^3\) of a saturated solution of L at 60\(^0\)C is cooled to 25\(^0\)C, what amount in mole will separate out?

A0.75

B0.25

C1.00

D0.50

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Question 716

jamb 2001

The diagram above represents the formation of

Aa metallic bond

Ban electrovalent bond

Ca covalent bond

Da coordinate covalent bond

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Question 717

jamb 2001

Use the graph above to answer this question.How long does it take all the solid to melt?`

A2.5 mins

B6.0 mins

C1.0 min

D3.0 mins

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Question 718

jamb 2001

Use the graph above to answer this question.If the gas is cooled, at what temperature will it start to condense?

A125 ^oC

B150^oC

C175^oC

D250^oC

View Explanation & Discuss

Question 719

jamb 2001

Which of the following gases contains the least number of atoms at s.t.p?

A1 mole of butane

B3 mole of ozone

C4 mole of chlorine

D7 mole of argon

View Explanation & Discuss

Question 720

jamb 2001

When sodium reacts with water, the resulting solution is

AWeakly acidic

BNeutral

CAcidic

DAlkaline

View Explanation & Discuss

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