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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.

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

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4,306 questions

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Question 911

neco 2009

When air is passed through alkaline pyrogallol and then lime water, the gases left are

Anitrogen and carbon (IV) oxide

Bnitrogen and noble gases

Cnitrogen and oxygen

Dnitrogen, carbon (VI) oxide and noble gases

Ethe noble gases

View Explanation & Discuss

Question 912

neco 2009

A salt which loses its mass when exposed to air is

Adeliquescent

Beffervescent

CEfflorescent

Dfluorescent

Ehygroscopic

View Explanation & Discuss

Question 913

neco 2009

Atomic size decreases

Aacross a period from left to right

Bacross a period from right to left

Cdiagonally down the group

Ddown a group

Ewith decrease in atomic number

View Explanation & Discuss

Question 914

neco 2009

Sulphur has an oxidation number of +4 in

AH₂S

BH₂S0₄

CMgSO₄

DNa₂SO₃

ES0₃

View Explanation & Discuss

Question 915

neco 2009

If the volume of a gas at 35°C is 60cm\(^3\), what would be its volume in cm\(^3\) at 273k?

A39.03

B46.81

C53.18

D67.69

E76.92

View Explanation & Discuss

Question 916

neco 2009

C\(_6\)H\(_{12}\)O\(_6\)

What is the molar mass of the compound above?

[ H=1, C=12, O=16 }

A45

B61

C180

D123

E244

View Explanation & Discuss

Question 917

neco 2009

In the electrolysis of dilute tetraoxosulphate (VI) acid using platinum electrodes, the products obtained at the anode are cathode respectively are

Ahydrogen, oxygen

BHydrogen, tetraoxosulphate (VI) ion

Coxygen, hydrogen

Dsulphur, hydrogen

Esulphur, oxygen

View Explanation & Discuss

Question 918

neco 2009

A neon atom is chemically nonreactive because

Athe electrons at the outermost shell is partially filled

Bthe number of protons equals the number of electrons

Cthe outer electron shell is completely filled

Dthere are equal number of protons and neutrons in its nucleus

Ethere are no elections at the outermost shell

View Explanation & Discuss

Question 919

neco 2009

\( ^{235}_{92}U + ^1_0n → ^{145}_{56}Ba + ^{88}_{36}Kr + 3^1_0n + Energy \)

The equation above represent a/an

Aalpha particle emission

Bendothermic reaction

Cnuclear fission

Dnuclear fusion

Ethermal dissociation

View Explanation & Discuss

Question 920

neco 2009

Which of these compounds has the greatest ionic character?

AAlF₃

BBF₂

CCF₄

DCsF

ENaF

View Explanation & Discuss

Question 921

neco 2009

What kind of bond exist between carbon and oxygen in C0₃ ^2-?

ACo- ordinate Covalent

Bcovalent

CElectrovalent

DMetallic

EVan der Waal forces

View Explanation & Discuss

Question 922

neco 2009

Which of the following gases will bleach moist litmus paper?

ACl₂

BCO₂

CHCl

DN₂O

ESO₃

View Explanation & Discuss

Question 923

neco 2009

Which of the following compounds will undergo thermal dissociation?

AAgCl

BCaCO₃

CK₂S0₄

DNaOH

ENH₄CI

View Explanation & Discuss

Question 924

neco 2009

The rate of a reaction usually increases with increase in the concentration of reactants because the

Adistance between particles of the reactants increases

Bfrequency of collision of particles is lower

Cparticles of the reactants gain energy and move faster

Dreactants from a complex which decomposes rapidly

Ereactants occupy a higher energy level

View Explanation & Discuss

Question 925

neco 2009

The reaction of an alkanol with alkanioc acid is known as

Adehydration

Besterification

Chalogenation

Dhydrogenation

Esaponification

View Explanation & Discuss

Question 926

neco 2009

The empirical formula of a hydrocarbon containing 0.12 mole of carbon 0.3 mole of hydrogen is

ACH₂

BCH₃

CC₂H₂

DC₂H₄

EC₂H₆

View Explanation & Discuss

Question 927

neco 2009

Which of the following statements is NOT correct of group VII elements? They

Aare diatomic

Bare good oxidizing agents

Care highly electronegative

Dhave high electron affinity

Ehave relatively low ionization potentials

View Explanation & Discuss

Question 928

neco 2009

Which of the following is NOT a fraction of petroleum?

ABitumen

BCoal

CDiesel

DKerosene

EPetrol

View Explanation & Discuss

Question 929

neco 2009

The scientist who discovered the zig-zag movement of gas molecules is

ABrownian

BDalton

CGay Lussac

DGraham

ENewton

View Explanation & Discuss

Question 930

neco 2009

The following compounds decolorize acidified potassium tetraoxomanganate (VII) solution EXCEPT

AHOCH₂ – CH₂OH

BH₂C –C =C– CH₃

CH₃C – HC = CH₂

DH₂C = CH₂

EH₃C – C =CH

View Explanation & Discuss

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