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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.

48 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

48 questions

Question 1 of 20 48 total questions

Question 1

jamb 1978

The size (diameter) of five elements are in the order R < T < W < X < Y, Y being the largest. If each atom has an electron situated on its circumference, and neglecting other factors, which of the atoms will lose its electron most reluctantly?

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Question 2

jamb 1978

Five compounds R,T,W,X and Y form the following compounds: a basic hydride R.H, an acidic hydride YH, atmospheric oxide W₂O₃, XO₂. which of the elements is an alkali

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Question 3

jamb 1978

An experiment test of the Law of conservation of Mass is illustrated in the diagram. In practice, the flask is weighed before and after reaction between solutions X and Y. Which of the following pairs of solutions will be unsuitable for the experiments

AX = hydrochloric acid; Y = silver nitrate

BX = barium chloride; Y = dilute sulphuric acid

CX = hydrochloric acid; Y = sodium hydroxide

DX = hydrochloric acid; Y = lead nitrate

EX = hydrochloric acid; Y = sodium carbonate

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Question 4

jamb 1978

Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100\(^o\)C, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0\(^o\)C?

AX only

BY only

CZ only

DX and Z

EY and Z

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Question 5

jamb 1978

A solid X when heated gives off a brown gas. If X is soluble in excess sodium hydroxide solution but insoluble in excess ammonium hydroxide solution, then X is

Abasic lead carbonate

Blead (II) nitrate

Csodium carbonate

Dzinc nitrate

Esodium nitrate

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Question 6

jamb 1978

Which of the five atoms can be described by the following properties: Relative atomic mass is greater than 30 but less than 40, it has odd atomic number and forms a unipositive ion in solution?

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Question 7

jamb 1978

Which of the following substances would you see as an indicator in the titration of sodium carbonate solution against hydrochloric acid (complete neutralisation)?

ALitmus paper

BPhenolphthalein

CMethyl orange

DUniversal indicator

ENone of these

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Question 8

jamb 1978

You are provided with five gas jars containing SO2, CO2, H2, CO and NO respectively. Select a test from A to E which will identify ANY ONE of the gases completely

Apass each gas into lime water

Bpass each gas into water and test with litmus paper

Cpass each gas into concentrated sulphuric acid

Dexpose each gas to atmospheric air

Eexpose each gas to fumes of hydrogen chloride

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Question 9

jamb 1978

A gas jar was inverted over burning yellow phosphorus floating over water in a beaker. After burning, the water level was found to rise in the gas jar. The water level rises because

Apressure inside the gas jar is greater than pressure outside it

Bthe air in the gas jar had been used up by burning

Coxygen in the gas jar had been used up by burning

Dnitrogen in the gas jar had been used up by burning

Ethe temperature in the jar had risen considerably

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Question 10

jamb 1978

In titration involving sodium hydroxide and dilute hydrochloric acid, where would you place the base?

Ain the beaker

Bin the conical flask

Cin a burette

Din the standard flask

Ein the measuring cylinder

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Question 11

jamb 1978

By means of filtration, one component can be obtained pure from an aqueous mixture of sodium chloride and?

Apotassium nitrate

Bsand

Clead nitrate

Dsugar (glucose)

Estarch

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Question 12

jamb 1978

Which of the following changes is physical?

AAdding iron filing to aerated water

BAdding sodium metal to water

CCooling a solution of Iron (II) sulphate to obtain the hydrated salt

DCooling water to obtain ice

EBurning the domestic gas (Utilgas) for cooking

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Question 13

jamb 1978

If hydrogen sulphide gas is passed into a solution of a pure iron chloride, a yellow deposit appears. If the deposit is filtered, a pale green solution is left behind. The pale green solution is

Adilute sulphuric acid

Bdilute hydrochloric acid

Cunreacted hydrogen sulphide in water

Diron (III) chloride

EIron (II) chloride

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Question 14

jamb 1978

Consider the following equation H2O + 2Fe2+ + Cl2 ↔ 2Fe3+ + 2Cl- + H2O. Which behaves as an oxidizing agent?

AFe²⁺

BCl₂

CFe³⁺

DCl^-

EH₂O

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Question 15

jamb 1978

Two gas cylinders contain ethylene (ethene) and acetylene respectively. One test which can be used to distinguish between them is by?

Apassing each gas through bromine water

Bpassing each gas through dilute potassium permanganate solution

Cpassing each gas through silver nitrate solution

Dtreating each gas catalytically with excess hydrogen gas

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Question 16

jamb 1978

Three solutions contain carbonate, sulphate and sulphide ions respectively. One test that will identify just ONE of them completely is by addition to each of them of

Abarium chloride solution

Bdilute hydrochloric acid

Clead nitrate solution

Dcalcium chloride solution

Esodium hydroxide solution

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Question 17

jamb 1978

If excess zinc is added to a bluish green solution of copper (II) sulphate, and the excess zinc filtered off after completion of reaction, a colourless solution is obtained because

Aboth zinc and copper are metals

Bthe sulphate radical and the zinc ion are divalent

Czinc is more electropositive than copper

Dboth zinc and copper form depositive ions in solution

Ezinc is a reducing agent

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Question 18

jamb 1978

Consider the following exothermic reaction
2SO_2(g) + O_2(g) ↔ 2SO_3(g)
If the temperature of the reaction is reduced from 800°C to 500°C, an no other change takes place, then

Athe reaction rate increases

Bconcentration of SO₃ decreases

Cconcentration of SO₃ increases

DSO₂ gas becomes unreactive

EO₃ gas becomes unreactive

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Question 19

jamb 1978

The most common type of chemical reaction which alkanes undergo is

Asubstitution

Baddition

Ccondensation

Dpolymerisation

Edouble decomposition

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Question 20

jamb 1978

Which of the following compounds will form a solution if exposed to air?

ANa₂CO₃.10H₂O

BNaNO₃

CCuSO₄

DCaCl₂

ENa₂SO₄.10H₂O

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