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Chemistry Past Questions

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47 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

47 questions

Question 1 of 20 47 total questions

Question 11

jamb 1980

Hardening of an oil may achieved by?

Aboiling the oil with water

Bboiling the oil with a catalyst

Ctreating the oil with sodium hydroxide

Dtreating the oil with hydrogen and catalyst

Edistilling oil under reduced pressure

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Question 12

jamb 1980

Hardening of an oil may be achieved by?

Aboiling the oil with water

Bboiling the oil with a catalyst

Ctreating the oil with sodium hydroxide

Dtreating the oil with hydrogen and catalyst

Edistilling oil under reduced pressure

View Explanation & Discuss

Question 13

jamb 1980

Which of the following does NOT happen when a zinc rod is introduced into a solution of copper (ll) sulphate?

AElectrons flow towards the zinc rod

BThe zinc rod dissolves

CThe temperature of the soil changes

DThe blue colour of the solution gradually disappears

ECopper metal is deposited

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Question 14

jamb 1980

The chemical reaction which takes place at the anode (positive electrode) in electrolysis is?

Aoxidation

Bhydrolysis

Cdissociation

Dreduction

Edisproportionation

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Question 15

jamb 1980

Which of the following silver halides is readily soluble in ammonium hydroxide?

AAgl

BAgBr

CAgCl

DAgF

ENone of the above

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Question 16

jamb 1980

In which of the following is the oxidation state of oxygen different from its value in water?

AOH^-

BH₃O⁺

CO^-

DH₂O₂

ESO₂

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Question 17

jamb 1980

When dilute hydrochloric acid is added to iron(ll)sulphide, the gas evolved will?

Aturn moist red litmus paper blue

Bturn lime water milky

Cblacken lead acetate paper

Drekindle a glowing splint

Eburn a sqeakly pop

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Question 18

jamb 1980

Given the mean atomic mass of chlorine prepared in the laboratory to be 35.5 and assuming that chlorine contains two isotopes of mass number 35 nad 37, what is the percentage composition of the isotope of mass number 35?

A20

B25

C50

D75

E90

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Question 19

jamb 1980

Which of the following is acceptable as the organic product of the reaction of ethanoic acid and ethanol with an acid catalyst?

AEthyl ethanoate

BMethyl ethanoate

CEthyl methyl ketone

DButanol

ENone

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Question 20

jamb 1980

20 cm3 of 1 M H\(_2\)SO\(_4\) is mixed 20 cm\(^3\) of 1 M NaOH. The resulting solution is?

Aacidic with a molarity of 0.50 M H₂SO₄

Bacidic with a molarity of 0.25 H₂SO₄

Cneutral

Dalkaline with a molarity of 0.25 M NaOH

Ealkaline with a molarity of 0.50 M NaOH

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Question 21

jamb 1980

When ethene gas reacts with chlorine gas to form 1, 2-dichloroethene, the reaction is called?

Asubstitution

Baddition

Cpolymerization

Dhydrolysis

Ereduction

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Question 22

jamb 1980

Which ONE of the following statements is true?

AAll alkali metals salts dissolves with dissociation in water

BMost ionic substances are easily vaporized

CIonic substances exist only as liquid

DNon-ionic substances are good electrolytes

ENitrogen exists in a trivalent state in ammonium salts

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Question 23

jamb 1980

Element X has a total of 19 electrons and can react with oxygen to form an oxide. Which of the following statements is NOT true of the oxide of the element?

AWhen exposed to air, it slowy changes to liquid

Bits solution in water conducts electricity

CIts solution in water, on evaporationm gives a white solid

DIts solution in water liberates hydroge when in contact with aluminium metal

EIts oxide, when stronlgy heated, regenerates the elements X

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Question 24

jamb 1980

Chlorine, bromine and iodine resemble each other in that all?

Adissolve in alkalis

Breact violently with hydrogen without heating

Cdisplace each other from solutions of their salts

Dare gases

Eare liquids

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Question 25

jamb 1980

The boiling point of water is higher than that of methanol because?

Awater is oxide while methanol is an alcohol

Binter molecular forces in water are stronger than those in methanol

Cwater is an inorganic compound while methanol is organic

Dwater is an ionic compound while methanol is a covalent compound

Ewater is more reactive than methanol

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Question 26

jamb 1980

Which of the following statements is true?

AMetals conduct electricity while non-metals do not

BMetals have high density, non-metals have low density

CMetals form basic oxides, non-metals form acidic oxides

DIn the electro chemical series, metals are above hydrogen while non-metals are below hydrogen

EMetals lose elections while non-metals gain electron during chemical reactions

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Question 27

jamb 1980

Which of the following statements is an exception in the assumptions of the kinetic theory of gases?

AGases are composed of many elastic particles

BThe particles are of negligible size

CThe particles are in constant random motion

DThe particles are of negligible mass

EThe particles collide with each other

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Question 28

jamb 1980

How many grams of hydrogen gas will be liberated when 6g of magnesium ribbon dissolves in 500cm³ of 6M HCl?

(Mg=24, H=1, Cl=35.5)

A1.2 g

B0.7 g

C0.5 g

D0.3 g

E0.12 g

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Question 29

jamb 1980

Under high pressure, real gases do not obey gas laws because their molecules?

Ahave become more energetic

Bhave become less energetic

Chave become smaller in size

Ddecompose into atoms

Estart repelling each other

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Question 30

jamb 1980

Which of the following reactions is correct as as written?

AFeCl₂ + 3NH₄OH → Fe(OH)₃ + 3NH₄Cl

BPb₂O₃ + 4HCl → PbCl₂ + 2H₂O

CPbNO₃ + H₂S → PbS + 2HNO₃

DNaOH + H₂SO₄ → NaHSO₄ +H₂O

E2NH₄NO₃ → N₂ + 2H₂O

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