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Chemistry Past Questions

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

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4,306 questions

Question 1 of 20 4,306 total questions

Question 1401

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 1402

waec 2000

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

ASulphur

BMagnesium

CAluminium

DZinc

View Explanation & Discuss

Question 1403

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 1404

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 1405

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 1406

waec 2000

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

AGlucose

BMaltose

CSucrose

DFructose

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Question 1407

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 1408

waec 2000

C8H18 will undergo the following reactions except

Acracking

Bcombustion

Csubstitution

Daddition

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Question 1409

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 1410

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 1411

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 1412

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 1413

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 1414

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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Question 1415

waec 2000

What is the value of x in the following equation? Cr2O72- + 14H+ + xe- → 2Cr3+ + 7H2O

D12

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Question 1416

waec 2000

Which of the following will displace copper from a solution of copper (ll) salt?

AAluminium ions

BMagnesium

CSilver

DZinc ions

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Question 1417

waec 2000

A finely divided form of a metal burns more readily in air than the rod form because the rod has

Ahigher molar mass

Bsmaller surface area

Cprotective oxide coating

Ddiferent chemical properties

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Question 1418

waec 2000

What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO2 + O2 ⇌ 2SO3; ∆H = - xKJmol-1

ADecreases the value of ∆H

BIncreases the collision rate of reactant particles

CShifts equilibrium position to the right

DReduces the time for attainment of equilibrium

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Question 1419

waec 2000

Chemical equilibrium is attained when

Areactants in the system are used up

Bconcentrations of the products are greater than those of the reactants

Cconcentrations of the reactants and products remain constant

Dreactants stop forming the products

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Question 1420

waec 2000

What type of reaction is involved when wood shavings produce a brown gas with concentrated HNO3?

ARedox reaction

BDestructive distillation

CDehydration

DNutralization

View Explanation & Discuss

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