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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 2131

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

View Explanation & Discuss

Question 2132

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

View Explanation & Discuss

Question 2133

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 2134

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 2135

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 2136

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

View Explanation & Discuss

Question 2137

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 2138

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 2139

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 2140

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 2141

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

View Explanation & Discuss

Question 2142

jamb 1978

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

AFe²⁺

BCl₂

CFe³⁺

DCl^-

EH₂O

View Explanation & Discuss

Question 2143

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

View Explanation & Discuss

Question 2144

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

View Explanation & Discuss

Question 2145

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

View Explanation & Discuss

Question 2146

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 2147

jamb 1978

The most common type of chemical reaction which alkanes undergo is

Asubstitution

Baddition

Ccondensation

Dpolymerisation

Edouble decomposition

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Question 2148

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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Question 2149

jamb 1978

The normal boiling point of a liquid is defined as?

Athe temperature at which its vapour pressure equals the atmospheric pressure

Bthe temperature at which bubbles begin to form

Cthe temperature at which the vapour pressure equals 1 temperature

Dthe temperature at which the rate of condensation of vapour equals the rate of vaporisation of the liquid

Ethe temperature at which the space above the liquid is saturated

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Question 2150

jamb 1978

Hypochlorous acid is used as a bleach because

Ait is a strong acid

Bit yields chlorine readily in pure water

Cit is an oxidising agent

Dit is a weak acid

Eit is a reducing agent

View Explanation & Discuss

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