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Chemistry Past Questions

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81 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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81 questions

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Question 11

waec 1990

Which of the following correctly explains entropy?

Athe natural tendency for a system to achieve a greater disorder

Ba balance of two driving forces between free energy and enthalpy changes

Cthe cause of spontaneity of a reaction

Da measure of the enthalpy of a reaction

Ea measure of the rate of attaining equilibrum in a reversible reaction

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Question 12

waec 1990

How many molecules are there in 14g of nitrogen gas at s.t.p? (n = 14, Avogadro Number = 6. 0 x \(10^{23 }\)mol-1)

A1.2 x 10 ²³

B3.0 x 10²³

C6.0 x10²³

D1.2 x 10²⁴

E30 x10²³

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Question 13

waec 1990

A catayst which increases the rate of a chemical reaction does so by

Aincreasing the reaction pathway

Bincreasing the surface area of the reactants

Cincreasing the pressure on the system

Ddecreasing the temperature at which the reaction occurs

Edecreasing the activation energy of the reaction

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Question 14

waec 1990

Which of the following reactions does not occur in the blast furnace during the extraction of iron?

AFe₂O₃ _(s) + 3CO_(g) → 2Fe_(l) + 3CO₂_(g)

BC₂ + CO ₂_(g)

CCaO_(s) + SiO₂_(s) → CaSiO ₃_(s)

DFeO_(s) + CO₂_(g) + Fe_(l)

E2Fe₂O_(s) → 4Fe_(l) 3O₂_(g)

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Question 15

waec 1990

Which of the following compounds will undergo additional reactions?

AEthyne

BButane

CPentane

DTetrachloromethane

EEthanol

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Question 16

waec 1990

When a solid melts and consequently boils, there is

Aa gradual increase in the average kinetic energy of the particles

Ba sudden decrease in the kinetic energy of the particles

Cno change in the average kinetic energy of the particles

Da rapid change in the nature of bonding of the components

Ea change in the size of the fundamental particles

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Question 17

waec 1990

Aluminum is above iron in the electrochemical series, yet iron corrodes easily on exposure to air while aluminium does not. This is because aluminium

Ahas a lower density than iron

Bis a better conductor than iron

Cdoes not corrode spontaneously

Dforms thin layer of inert oxide in moist air

Eforms amphoteric oxides while iron does not

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Question 18

waec 1990

The heat accompanying the reaction represented by the equation H₂O _(l) → H ₂O_(g) is described as the heat of

Asolution

Bneutralization

Cvaporization

Dsublimation

Eactivation

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Question 19

waec 1990

The electronic configuration 1s^{2 2}2s ²2p ⁶3s²3p ⁶ is that of a

Anoble gas

BGroup ll element

CGroup lll element

DGroup V element

EGroup VI element

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Question 20

waec 1990

A sample of orange juice is suspected to have been contaminated with a yellow dye. Which of the following methods can be used to detect the dye?

ADecantation

BChromatography

CDistillation

DFiltration

EEvaporation

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Question 21

waec 1990

Which of the following reaction will not take place under normal conditions?

AZn_(s) + 2HCl → ZnCI_2(aq) + H _2(g)

BFe _(s) + H ₂SO_4(aq) → FeSO_4(aq) + H_2(g)

CCu _(s) + 2HCI _(aq) → CuCI _2(aq) + H_2(g)

DCa_(s) + 2H ₂O ₍₁₎ → Ca(OH)_2(g) + H_2(g)

E2Na_(s) + 2H ₂O ₍₁₎ → 2NaOH_(aq) + H_2(g)

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Question 22

waec 1990

Catalytic hydrogenation of oils results in the production of

Asoaps

Bdetergents

Calkanes

Dbutter

Emargarine

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Question 23

jamb 1990

The Avogadro number of 24g of magnesium is the same as that of

A1g of hydrogen molecules

B16g of oxygen molecules

C32g of oxygen molecules

D35.5g of chlorine molecules

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Question 24

jamb 1990

Select the right answer from the structure above.Which of the following compounds represents the polymerization product of ethyne?

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Question 25

jamb 1990

The above reaction is an example of

Aa displacement reaction

Ba neutralization reaction

Can elimination reaction

Dsaponification

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Question 26

jamb 1990

CH3-C = CH \(\frac{Na}{liq NH_3}\)> P, Compound P, in the above reaction, is

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Question 27

jamb 1990

What is the IUPAC name for the hydrocarbon?

A2-ethyl-4-methylpent-2-ene

B3,5-dimethylhex-3-ene

C2,4-dimethylhex 3-ene

D2-methyl-4-ethylpent-3-ene

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Question 28

jamb 1990

Use the graph above to answer this question. The structure of cis-2-butene is

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Question 29

jamb 1990

Changes in the physical in the scheme above.The letter X,Y and Z respectively represent

Asublimation, condensation and freezing

Bsublimation, vapourization and solidification

Cfreezing, condensation and sublimation

Devaporation, liquefaction and solidification

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Question 30

jamb 1990

0.1 faraday of electricity deposited 2.95 g of nickel during electrolysis of an aqueous solution.
Calculate the number of moles of nickel that will be deposited by 0.4 faraday?

(Ni = 58.7)

A0.20

B0.30

C0.04

D5.87

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