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Chemistry Past Questions

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1,623 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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1,623 questions

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Question 41

waec 2024

Naturally occurring Boron is made up of 19.9% \(^{10}\)B and 80.1% \(^{11}\)B. The relative atomic mass of Boron is

A21.0

B10.8

C10.5

D10.0

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Question 42

waec 2024

Consider the reaction represented by the equation:

C\(_3\)H\(_8\) + 5 O\(_2\) → 3CO\(_2\) + 4H\(_2\)O

If 0.1 mole of C\(_3\)H\(_8\) was completely burnt, what volume of CO\(_2\) would be produced at stp? [volume of gas at stp = 22.4dm\(^3\)mol\(^{-1}\)].

A6.72dm\(^3\)

B2.24dm\(^3\)

C0.30 dm\(^3\)

D0.10dm\(^3\)

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Question 43

waec 2024

Which of the following arrangements of elements is in order of increasing ionization energy?

ASi, Al, S, P

BS, P, Si, Al

CAl, Si, P, S

DP, Si, S, Al

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Question 44

waec 2024

Aluminium is suitable for making alloys for aircraft construction because it

Ais hard and brittle

Bis light and very resistant to corrosion

Chas high density and also a non-conductor of electricity

Dis amphoteric and allotropic

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Question 45

waec 2024

Which of the following statements describes transition elements? They

Aare very reactive

Bhave low melting points

Cpossess variable oxidation state

Dform colourless salts

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Question 46

waec 2024

The reaction represented by the equation: Ni\(^{2+}\)\((_{aq}\)) + Fe\((_s\)) → Ni\((_s\)) + Fe\(^{2+}\)\((_{aq}\)) is a redox reaction because

ANi\(^{2+}\) ions are oxidized and Fe acts as a oxidizing agent

BNi\(^{2+}\) ions are oxidized and Fe acts as a reducing agent

CNi\(^{2+}\) ions are reduced and Fe acts as an oxidizing agent

DNi\(^{2+}\) ions are reduced and Fe acts as a reducing agent.

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Question 47

waec 2024

At 25\(^0\)C, the saturated solution of a salt in water was found to contain 0.24g of the salt in 100cm\(^3\). What is the solubility of the salt in gdm\(^{-1}\)?

A0.024

B0.240

C2.40

D24.0

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Question 48

waec 2024

In ethanol, the attractive forces between adjacent molecules are

Acovalent bonds only

Bhydrogen bonds only

Chydrogen bonding and Van der Waal's forces

DVan der Waal's forces only

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Question 49

waec 2024

Which of the following functional groups is present in alkanoic acid?

A-COOH

B-OH

C-COOR

D-CHO

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Question 50

waec 2024

Ethanedioic acid is an organic solid that can be purified by

Adecantation

Bdistillation

Ccrystallization

Dfiltration

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Question 51

waec 2024

Which of the following statements about ammonium salt is correct? It

Adissolves in water to form solution of pH > 1

Bdissolves in water to form solution of pH < 7

Cdoes not decompose on heating

Dis insoluble in water

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Question 52

waec 2024

The product of the reaction between ethanol and excess acidified K\(_2\)Cr\(_2\)O\(_7\) is

ACH\(_2\)=CH\(_2\)

BCH\(_3\)OCH\(_3\)

CCH\(_3\)COOH

DCH\(_3\)CH\(_3\)

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Question 53

waec 2024

The product formed when concentrated sodium chloride solution is electrolysed using carbon electrodes is

Achloride water

Bhydrochloric acid

Csodium hydroxide

Dsodium oxochlorate (I)

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Question 54

waec 2024

Bases normally

Aare corrosive

Bturn litmus paper from blue to red

Cturn litmus paper from red to blue

Dare non-metal oxides

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Question 55

waec 2024

The most important ore of aluminium is

Abauxite

Bhaematite

Cmagnetite

Dmonazite

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Question 56

waec 2024

The oxidation number of Chromium in Na\(_2\)Cr\(_2\)O\(_7\) is

A+2

B+6

C+7

D+12

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Question 57

waec 2024

The electron configuration 1S\(^2\) 2S\(^2\) 2P\(_x\)\(^2\) contravenes the

APauli's exclusion principle

BAufbau's principle

Coctet rule

DHund's rule

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Question 58

waec 2024

The branch of science that deals with the nature and properties of substances and how one substance can be converted to another is known as

Abiology

Bchemistry

Cgeography

Dphysics

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Question 59

waec 2024

Which of the following substances has the lowest boiling point?

AAqueous sodium chloride

BEthanol

CTetrachloromethane

DWater

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Question 60

waec 2024

Which of the following gases could be collected by downward displacement of air?

AChlorine

BHydrogen

Chydrogen chloride

DSulphur(IV) oxide

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