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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.

168 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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168 questions

Question 1 of 20 168 total questions

Question 41

neco 2008

Which of the following is a component of the car exhaust?

AAluminium

BCalcium

CIron

DZinc

ELead

View Explanation & Discuss

Question 42

neco 2008

Which of the following will Increase the rate of reaction of Chips of a metal M as shown in the equation below?

M(s)+2HC1(aq) → MCI₂ (aq) + H₂(g)

AAdding some distilled water

BDecreasing the temperature

CDiluting the hydrochloric acid

DGrinding the metal into powder

EIncreasing the pressure

View Explanation & Discuss

Question 43

neco 2008

What is the colour of phenolphthalein indicator in a basic medium?

ABlue

BColourless

COrange

DPink

EYellow

View Explanation & Discuss

Question 44

neco 2008

\( ^{234}_{90}Th → ^{234}_{91}Pa + X \)
In the nuclear reaction above, X is

A\( ^0_1e \)

B\( ^0_{-1}e \)

C\( ^4_2He \)

D\( ^1_0n \)

E\( ^1_1p\)

View Explanation & Discuss

Question 45

neco 2008

When dust particles collide randomly in a beam of Sunlight, the phenomenon observed is known as

ABrownian movement.

BDialysis

CDiffusion

DOsmosis

ETyndall effect

View Explanation & Discuss

Question 46

neco 2008

The most efficient absorber of ultraviolet radiation in the atmosphere is

ACO₂

BH₂

CH₂O

D0₂

EO₃

View Explanation & Discuss

Question 47

neco 2008

Chlorine atom forms Cl- by

Adonating lone pair of electrons

Bgaining an electron

Closing an electron

Dsharing an electron

Esharing a lone pair of electrons.

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Question 48

neco 2008

Which of the following laws is obeyed If at constant temperature, 200cm of hydrogen at 1.5 × 10m⁵Nm^-2pressure becomes 300cm³ at 1.0 × 10⁵Nm^-2 pressure?

AAvogadro’s

BBoyle’s

CCharles’

DFaraday’s

EGraham’s

View Explanation & Discuss

Question 49

neco 2008

The type of reaction ethyne mainly undergoes is

Aaddition

Bcarboxylation.

Cesterification

Dsaponification

Esubstitution

View Explanation & Discuss

Question 50

neco 2003

What is the number of moles of Na\(_H\)CO\(_3\) in 250cm\(^3\) of its solution if the solution contains 8.4 g of Na\(_H\)CO\(_3\) in 1 dm\(^3\) of the solution. [Na = 23, 0 = 16, C = 12, H = 1)

B0.25

C0.05

D0.025

E0.01

View Explanation & Discuss

Question 51

neco 2003

In the reaction 2H₂S(g) + SO₂(g) → 2H₂SO(I)+3S(s)SO₂is acting as _agent

Aa bleaching

Ba dehydrating

Can oxidizing

Da precipitating

Ea reducing

View Explanation & Discuss

Question 52

neco 2003

What is the change in the oxidation number of phosphorus in the following reaction?

4P(s) + 5O₂(ag) → 2P₂O₅(s)

A0 to 2

B0 to 5

C4 to 2

D4 to 5

E4 to 10

View Explanation & Discuss

Question 53

neco 2003

Chlorine displaces bromine from aqueous potassium bromide because

Abromine is a liquid at room temperature

Bbromine is weakly acidic.

Cbromine has a greater atomic radius than chlorine

Dchlorine is a stronger oxidising agent than bromine.

Ethe density of chlorine is less than the density of bromine.

View Explanation & Discuss

Question 54

neco 2003

The pH of water is 7.

What is the pH of orange juice?

Babove 10

Cbelow 2

Dbetween 5.5 and 6.5

Ebetween 7.5 and 8.5

View Explanation & Discuss

Question 55

neco 2003

Small amounts of compounds of transition metals are sometimes added to glass during manufacture in order to make the glass

Aacquire certain colours

Beasier to melt

Ceasier to mould

Dlittle brittle

Emore transparent

View Explanation & Discuss

Question 56

neco 2003

Which separation technique is routinely applied in the petroleum industry?

Achromatography

Bdistillation

Cevaporation

Dfractional crystallization

Efractional distillation

View Explanation & Discuss

Question 57

neco 2003

Which metal is extracted from bauxite?

Aaluminium

Bcalcium

Ccopper

Dmagnesium

Etin

View Explanation & Discuss

Question 58

neco 2003

Why is tetraoxosulphate(VI) acid NOT used for making carbon dioxide from calcium carbonate? It is

Aa dehydrating agent

Ba strong acid

Can oxidising agent

Ddibasic

Eforms insoluble calcium tetraoxosulphate(Vl)

View Explanation & Discuss

Question 59

neco 2003

Which hydrocarbon does NOT exhibit structural isomerism?

AC₃H₆

BC₄H₆

CC₄H₈

DC₄H₁₀

EC₅H₁₂

View Explanation & Discuss

Question 60

neco 2003

What is formed when starch is completely hydrolysed?

Afructose

Bglucose

Clactose

Dmaltose

Esucrose

View Explanation & Discuss

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