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Chemistry Past Questions

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89 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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89 questions

Question 1 of 20 89 total questions

Question 31

jamb 2012

A piece of filter paper moistened with lead (ll) ethanoate solution turns black when the paper is dropped into a gas likely to be

Asulphur (VI) oxide

Bhydrogen chloride

Csulphur (VI) oxide

Dhydrogen sulphide

View Explanation & Discuss

Question 32

jamb 2012

The highest rate of production of carbon (lV) oxide can be achieved using

A0.05 mol ^-3HCI and 5g powdered CaCO₃

B0.05 mol ^-3HCI and 5g lump CaCO₃

C0.10 mol ^-3HCI and 5g powdered CaCO₃

D0.025 mol ^-3HCI and 5g powdered CaCO₃

View Explanation & Discuss

Question 33

jamb 2012

An increase in entropy can best be illustrated by

Amixing of gases

Bfreezing of water

Cthe condensation of vapour

Dsolidifying candle wax

View Explanation & Discuss

Question 34

jamb 2012

CO(g) + H\(_2\) O\(_{(g)}\) → CO\(_{2(g)}\) + H\(_{2(g)}\)
Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO\(_{2(g)}\), H\(_2\)O\(_{(g)}\) and CO\(_{(g)}\) in kJmol\(^{-1}\) are - 394, -242 and - 110 respectively.

A+ 262 KJ mol ^-1

B- 262 KJ mol ^-1

C+ 42 KJ mol ^-1

D- 42 KJ mol ^-1

View Explanation & Discuss

Question 35

jamb 2012

A metal M displaces zinc from ZnCl solution
This shows that

Aelectrons flow from zinc to M

BM is more electropositive than zinc

CM is more electonegative than zinc

Dzinc is more electropositive than M

View Explanation & Discuss

Question 36

jamb 2012

What number of moles of Cu 2+ will be deposited by 360 coulombs of electricity?
[f = 96500 C mol -1]

A5.36 x 10 ^-4 mole

B1. 87 x 10 10 ^-3 mole

C9. 35 x 10 ^-4 mole

D3. 73 x 10 ^-3

View Explanation & Discuss

Question 37

jamb 2012

2\(Na_2O_{2(s)} + 2H_2O_{(1)}\)→ 4\(NaOH_{(s)} +O_{2(g)}\)
The substance that is oxidized in the reaction above is

A\(Na_2O_{2(s)}\)

BNaOH(aq)

CH₂O₍₁₎

DO_2(g)

View Explanation & Discuss

Question 38

jamb 2012

The oxidation number of boron in NaBH ₄ is

A-3

B-1

C+1

D+3

View Explanation & Discuss

Question 39

jamb 2012

A major factor considered in selecting a suitable method for preparing a simple salt is its

ACrystalline from

Bmelting point

Creactivity with dilute acids

Dsolubility in water

View Explanation & Discuss

Question 40

jamb 2012

During a titration experiment, 0.05 moles of carbon (lV) oxide is liberated. What is the volume of gas liberated?

A22.40 dm ³

B11.20 dm ³

C2.24 dm ³

D1.12 dm ³

View Explanation & Discuss

Question 41

jamb 2012

The number of hydroxonium ions produced by one molecule of an acid in aqueous solution is its

Abasicity

Bacid strength

CpH

Dconcentration

View Explanation & Discuss

Question 42

jamb 2012

Which of the following will produce a solution with pH less than 7 at equivalent point?

AHNO ₃ +NaOH

BH ₂SO ₄ + KOH

CHCL +Mg (OH) ₂

DHNO ₃ + KOH

View Explanation & Discuss

Question 43

jamb 2012

Which of the following pollutants is associated with brain damage?

ACarbon (ll) oxide

BRadioactive fallout

CBiodegradable waste

DSulphus (lV) oxide

View Explanation & Discuss

Question 44

jamb 2012

Potassium trioxochlorate (V)has a solubility of 1.5 mol dm -3 at 45 oC.On cooling this solution to a temperature of 20 oC, the solubility was found to be 0.5 mol dm -3. What mass of KCIO 3 was crystalized out?
[K = 39, Cl = 35.5 O =16]

A1.00g

B10.00g

C12.25g

D122.50g

View Explanation & Discuss

Question 45

jamb 2012

The solubilites of different solutes in a given solvent can be compared by

Aplotting their solubility curves on separete axes

Bplotting their solubility curves on the same axes

Cplotting some of the solubility curves on the x-axis and others on the y-axis

Dplotting their solubility curves on the x-axis only

View Explanation & Discuss

Question 46

jamb 2012

Chlorination of water for town supply is carried out to

Amake the water colourless

Bremove germs from the water

Cmake the water tastedful

Dremove odour from the water

View Explanation & Discuss

Question 47

jamb 2012

The chemicals used to soften hard water involves the addition of

Ainsoluble sodium compounds which from soluble solutions of calcium and magesium

Bsolube soudium compounds which from soluble solutions of calcium and magnesium ions

Csolube sodium compounds which from insoluble precipitates of calcium and magnesium ions

Dinsoluble precipitates of calcium and magnesium ions

View Explanation & Discuss

Question 48

jamb 2012

I. It has a varied composition from one place to another. ll. it constituents can be separated by physical means
lll. It contains unreactive noble gases
which of the above shows that air is a mixture?

AI and ll only

Bll and lll only

Cl and lll only

Dl,ll and lll

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Question 49

jamb 2012

Which of the following is used to study the arrangement of particles in crystal lattices?

AAlpha-particles

BBeta-particles

CGamma-rays

DX-rays

View Explanation & Discuss

Question 50

jamb 2012

Group VII elements are

Amonoatmic

Bgood oxidizing agents

Chighly electropositive

Delectron donors

View Explanation & Discuss

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