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Chemistry Past Questions

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49 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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49 questions

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Question 21

jamb 1979

Which of the following statements is true? When the potassium atom forms its ion

Ait gains one electron and becomes neutral

Bits atomic number decreases

Cit achieves electronic configuration of orgon

Dit loses one proton

Eit loses one neutron

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Question 22

jamb 1979

Which of the following statements applies during the electrolysis of sodium hydroxide solution using platinum electrodes?

ANa⁺ ions are discharged at the cathode

BHydrogen ions are discharged at the cathode

Cthe concentration of sodium hydroxide decrease at both electrode compartments

Dthe concentration of sodium hydroxide increases at the cathode only

Ethe concentration of sodium hydroxide increases at the anode only

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Question 23

jamb 1979

Methanoic acid mixes with water in all proportions and has about the same boiling point as water which of the following methods would you adopt to obtain pure water from a mixture of stand, water and methanoic acid?

Afractional distillation

Bfiltration followed by distillation

Cneutralization with sodium hydroxide followed by distillation

Desterification with ethanol followed by distillation

Eneutralization with sodium hydroxide followed by filtration

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Question 24

jamb 1979

When carbondioxide is bubbled into limewater a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is

Acalcium carbonate is formed which on reaction dissolves

Bcalcium hydrogen carbonate is precipitated and then dissolves

Ccalcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate

Dconcentration of the solution has occurred with the deposition of calcium hydroxide

Ethe solution has become saturated and solid carbondioxide has been deposited

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Question 25

jamb 1979

The oxidation state of manganese in potassium permanganate is

A+7

B+5

C+3

D+2

E+1

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Question 26

jamb 1979

The reaction of zinc with copper (ll) ions in aqueous solution can be represented as follows: Cu ²⁺(aq) +Zn (s) → Cu(s) + Zn ²⁺(aq).Which of the following is the most complete description of this reaction?

ACpper (ll) ions are being reduced

BZinc is being oxidized.

CCopper (ll) ions and zinc are being reduced

Dcopper (ll) ions and zinc are being oxidized

Ecopper(ll) ions are being reduced and zinc oxidized

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Question 27

jamb 1979

Which of the following substances are all made by the process of polymerization?

ANylon and soap

BEthanoic acid margarine and ethanol

CNylon and artificial rubber

DSoap and butane

EMargarine and nylon

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Question 28

jamb 1979

Which are the correct IUPAC names for H-CO\(_2\)CH\(_3\) and CH \(\equiv\) CH

AMethyl methanoate and ethene

BMetanoic acid and ethyne

CEthyl methanoate and ethyne

DMethyl methanoate and ethyne

EEthanoic acid and ethene

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Question 29

jamb 1979

An organic compound X has the following properties: I. It is not miscible with water. ll. lt has boiling point of 77^oC lll. lt has a sweet odour lV. lt is insoluble in sodium hydrogen carbonate solution . V lt does not decolourize bromine water X is therefore

Amethane

Bethanoic acid

Cethene

Dethyl ethanoate

Ecarbon tetrachloride

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