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Chemistry Past Questions

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2,505 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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2,505 questions

Question 1 of 20 2,505 total questions

Question 1221

jamb 1979

In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:
Anode Cathode

ASulphur hydrogen

BHydrogen oxygen

COxygen Hydrogen

DHydrogen sulphate ions

ESulphur oxygen

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Question 1222

jamb 1979

12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 oC. The solubility of potassium chlorate at 66 oC is therefore?

A66

B33

C10

D20

E30

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Question 1223

jamb 1979

If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while

Athe solution will give out chlorine gas and hydrogen chloride gas

Bthe solution will produce chlorine gas and oxygen

Cthe solution will give out solution will producing hypochloric acid

Dthe solution is decomposed giving out oxygen, hydrogen and chlorine

Ethe solution will give out oxygen gas leaving behind aqueous hydrochloric acid

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Question 1224

jamb 1979

When ammonium, potassium and calcium carbonates are each separately heated

Anone of them will decompose

Beach of them will decompose to give carbondioxide and the respective oxide

Cammonium carbonate and potassium carbonate will not decompose

Donly ammonium carbonate and the respective oxide

Eammonium carbonate will decompose to give carbondioxide, water and ammonia

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Question 1225

jamb 1979

How many grams of HBr would exactly be required to react with 2 g of propyne? (C =12, H=1, Br = 80)

A4. 1 g

B6. 1 g

C8. 1g

D16.2g

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Question 1226

jamb 1979

\(50cm^{3}\) of hydrogen are sparked with \(20cm^{3}\) of oxygen at \(100°C\) and \(1atm\) . The total volume of the residual gases in

A50 cm³

B10 cm³

C40 cm³

D30 cm³

E70 cm³

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Question 1227

jamb 1979

Helium atoms are chemically unreactive because

Athere are no electrons around the nucleus

Bthe number of protons equals the number of electrons

Cthere are equal number of protons and neutrons in the nucleus

Dthe outer electron shell is completely filled

Ethe atoms contain only protons

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Question 1228

jamb 1979

Which of the following contains two amphoteric oxides?

Asodium oxide, Zinc oxide , Magnesium oxide

BAluminium oxide, Calcium oxide, Zinc oxide

CPotassium oxide, Lithium oxide, Carbon monoxide

DSilver oxide, Lead oxide, Sodium oxide

ESulphur dioxide, Aluminium oxide, Carbon monoxide

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Question 1229

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 1230

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 1231

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 1232

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 1233

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 1234

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 1235

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 1236

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 1237

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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Question 1238

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 1239

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 1240

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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