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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.

95 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

95 questions

Question 1 of 20 95 total questions

Question 1

waec 2000

P,Q,R and S are metals in the same group in the Periodic Table but in periods 3,4, 5 and 6 respectively which of them loses electrons least readily?

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Question 2

waec 2000

Given that the electronic configuration of an element X is 1s22s22p63s 23p4, it can be deduced that X

Abelongs to group VI in the Periodic Table

Bbelongs to periodic Table

Ccontains 3 unpaired electrons in the ground state

Dhas atomic number 27

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Question 3

waec 2000

What is the mass number of an element if its atom contains 10 protons, 10 electrons and 12 neutrons?

A32

B22

C20

D10

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Question 4

waec 2000

Allotropes of an element differ in their

Aphysical properties

Bchemical properties

Cmass numbers

Delectronic configuration

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Question 5

waec 2000

A plastic which cannot be softened by heat is described as

Athermosetting

Bnon-biodegradable

Cthermoplastic

Dmalleable

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Question 6

waec 2000

Biotechnology is applied in the following except

Abaking industry

Bwine production

Cproduction of antibiotics

Dmanufacture of soap

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Question 7

waec 2000

If 20 cm3 of distilled water is added to 80 cm3 of 0.50 mol dm-3 hydrochloric acid, the concentration of the acid will change to

A20 mol dm^-3

B0.40 mol dm^-3

C2.00 mol dm^-3

D5.00 mol dm ^-3

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Question 8

waec 2000

Which of the following on burning in air contributes to acid rain?

ASulphur

BMagnesium

CAluminium

DZinc

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Question 9

waec 2000

When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate formed re-dissolves in excess sodium hydroxide because

Asodium is more reactive than zinc

Bsodium hydroxide is a strong alkali

Czinc hydroxide is amphoteric

Dzinc hydroxide is unstable

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Question 10

waec 2000

A colourless, odourless liquid T, gives effervescence with sodium trioxocarbonate (IV) and a white precipitate with silver trioxonitrate (V) solution T is most probably

Asodium chloride solution

Bbarium chloride solution

Cdilute trioxonitrate (V) acid

Ddilute hydrochloric acid

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Question 11

waec 2000

Two-organic substances are labelled K and L if K gave a blue-black colour with iodine solution and L gave a deep red precipitate with Million's reagent, it can be concluded that

AK is a carbohydrate and L is a protein

BK is alkaline and L is acidic

CK is unsaturated and L is a reducing sugar

DK is a reducing agent and L is an amino acid

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Question 12

waec 2000

Which of the following needs to be hydrolyzed before it shows reducing property?

AGlucose

BMaltose

CSucrose

DFructose

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Question 13

waec 2000

Which of the following is correct about both compounds shown below? CH3CH 2CH2OH;CH 3
CH 2CH(OH)CH3

AThey have identical physical properties

BThey are structural isomers

CTheir general molecular formula is the same

DThey are oxidized to alkanones

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Question 14

waec 2000

C8H18 will undergo the following reactions except

Acracking

Bcombustion

Csubstitution

Daddition

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Question 15

waec 2000

2 moles of hydrogen gas will react completely with one mole of....

ACH₂=CHCl

BCH₃-CH=CH₂

CC₆H₅-CH₃

DCH≡C-CH₂-CH₃

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Question 16

waec 2000

Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?

Acarry out some food tests

Bexamine the pastry sample under a microscope

CDo a chromatogram of the colouring extract

D.determine the molar mass of the colouring

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Question 17

waec 2000

Which of the following occurs when a solution of CuSO4 is electrolysed using copper electrodes?

AThe cathode becomes coated with copper

BBoth electrodes gain electrons

CThe blue colour of the solution fades gradually

DThe anode increases in mass

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Question 18

waec 2000

0.10 mol dm-3 NaCI conducts electricity better than 0.10 mol dm-3 CH3COOH because the solution of NaCI

Acontains more ions

Bis neutral to litmus

Chas a lower molar mass

Dhas a higher pH

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Question 19

waec 2000

An iron nail placed in a solution copper (ll) tetraoxosulphate (VI) is soon covered with a deposit of copper. Which of the following equations represents the reactions ?

AFe ²⁺ _(aq) + Cu_(s) → Fe ³⁺ + Cu ²⁺ _(aq)

BFe ²⁺ _(aq) + Cu_(s) → Fe_(s) + Cu²⁺ _(aq)

CFe _(s) + Cu²⁺ _(aq) → Fe²⁺_(aq) + Cu²⁺ _(aq)

DFe_(s) + Cu²⁺ → Fe²⁺_(aq) + Cu_(s)

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Question 20

waec 2000

In which of the following is the oxidation number of sulphur equal to -2?

AS₈

BH₂S

CSO ₂

DSO ₃ ^2-

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