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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.

92 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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92 questions

Question 1 of 20 92 total questions

Question 21

waec 2004

Which of the following electron transition results in the emission of energy?

A3p to 3s

B3p to 4p

C2s to 2p

D1s to 2s

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Question 22

waec 2004

The mass of an element is 27 and its atomic number is 13. What is the composition of the nucleus of its atom?

A13 electrons and 14 protons

B13 neutrons and 14 protons

C13 protons and 14 neutrons

D13 electrons and 14 neutrons

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Question 23

jamb 2004

The IUPAC nomenclature of the compound above is

A2-ethylpentane

B3,4-dimethylhexane

C2,3-dimethylhexane

D2-ethylhexane

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Question 24

jamb 2004

In the experiment above, X is a mixture of nitrogen, carbon (IV) oxide and

Awater

Bimpurities

Cinert gas

Doxygen

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Question 25

jamb 2004

In the production of soap, concentrated sodium chloride solution is added to

AIncrease the solubility of soap

BDecrease the solubility of the soap

CSaponify the soap

DEmulsify the soap

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Question 26

jamb 2004

Alkanol + Alkanoic acid ⇌ Ester + Water
The reverse reaction above is known as

AHydrolysis

BSaponification

CHydration

DFermentation

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Question 27

jamb 2004

C\(_2\)H\(_5\)OH(aq) → Y
If the above reaction takes place in conc. H\(_2\)SO\(_4\) at 180\(^0\)C, Y represents

ACH₄

BC₂H₅COOH

CC₂H₄

DCH₃OCH₃

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Question 28

jamb 2004

CH\(_3\)COOH(g) → CH\(_4\)(g) + CO\(_2\)(g)
The reaction above is

ACarboxylation

BDecarboxylation

CAcidification

DEsterification

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Question 29

jamb 2004

Vulcanization involves the removal of

Aa monomer

Bthe single bond

Cthe double bond

Da polymer

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Question 30

jamb 2004

Which of these reagents can confirm the presence of a triple bond?

ABromine water

BAcidified KMnO₄

CCopper (I) chloride

DBromine gas

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Question 31

jamb 2004

A characteristic of the alkane family is

AAddition reaction

BElimination reaction

CSubstitution reaction

DNeutralization reaction

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Question 32

jamb 2004

An isomer of C\(_5\)H\(_{12}\) is

AButane

B2 – methylbutane

C2 – methylpropane

D2 – ethylbutane

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Question 33

jamb 2004

The alkyl group can be represented by the general formula

AC_nH_2n+1

BC_nH_2n

CC_nH_2n+2

DC_nH_2n-2

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Question 34

jamb 2004

Oxyacetylene flame is used for iron-welding because it

AMakes the iron metals solidify very quickly

BCombines with oxygen to give a pop sound

CEvolves a lot of heat when burnt

DDissociates to produce carbon (IV) oxide and oxygen

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Question 35

jamb 2004

Sodium metal is always kept under oil because it

AReadily reacts with water

BIs reduced by atmospheric nitrogen

CReacts vigorously on exposure to air

DReacts with oxygen and carbon (IV) oxide

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Question 36

jamb 2004

Transition metals possess variable oxidation states because they have

AElectrons in the d orbitals

BElectron in the s orbitals

CA variable number of electrons in the p orbitals

DPartially filled p orbitals

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Question 37

jamb 2004

Alloys are best prepared by

AElectroplating

BArc-welding

CReducing and mixture of their metallic oxide

DCooling a molten mixture of the metals

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Question 38

jamb 2004

Aluminium hydroxide is used in the dyeing industry as a

ASalt

BDye

CMordant

DDispersant

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Question 39

jamb 2004

Carbon is tetravalent because

AThe electrons in both the 2s and 2p orbitals are equivalent

BThe electrons in all the orbitals of carbon are equivalent

CThe 2s and 2p atomic orbitals hybridize

DAll the atomic orbitals of carbon hybridize

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Question 40

jamb 2004

Sulphur (IV) oxide bleaches by

AReduction

BOxidation

CHydration

DAdsorption

View Explanation & Discuss

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