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Chemistry Past Questions

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51 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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51 questions

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Question 21

jamb 1985

A man suspected of being drunk is made to pass his breath into acidified potassium dichlormate solution. If his breath carries a significant level of ethanol, the final colour of the solution is?

Apink

Bpurple

Corange

Dblue-black

Egreen

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Question 22

jamb 1985

Which of the following is used in the manufacture of bleaching powder?

ASulphur dioxide

BChlorine

CHydrogen tetraoxosulphate (VI)

DHydrogen sulphide

ENitrogen dioxide

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Question 23

jamb 1985

Complete hydrogenation of ethyne yields?

Abenzene

Bmethane

Cethane

Dethene

Epropane

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Question 24

jamb 1985

In the reaction H2(g)O \(\to\) H2(g) + 1/2O2(g)

ΔH = -2436000 KJ, which of the following has no effect on the equilibrium position?

AAdding argon to the system

BLowering the temperature

CAdding hydrogen to the system

DDecreasing the pressure

EIncreasing the temperature

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Question 25

jamb 1985

Which of the following metals will displace iron from a solution of iron(ll)tetraoxosulphate(lV)?

ACopper

BMercury

CSilver

DZinc

EGold

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Question 26

jamb 1985

2MnO^-₄ + 10Cl^- + 16H⁺ → 2Mn²⁺ + 5Cl₂ + 8H₂O. Which of the substances serves as an oxidizing agent?

AMn²⁺

BCl^-

CH₂O

DMnO^-₄

ECl₂

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Question 27

jamb 1985

A certain industrial process is represented by the chemical equation 2A_(g) + B_(g) \(\to\) C_(g) + 3D_(g) \(\Delta\)H = X kJmol^-1. Which of the following conditions will favour the yield of the products?

Aincrease in temperature, decrease in pressure

Bincrease in temperature, increase in pressure

Cdecrease in temperature,increase in pressure

Ddecrease in temperature, decrease in pressure

Econstant in temperature, increase in pressure

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Question 28

jamb 1985

A correct electrochemical series can be obtained from K, Na, Ca, Al, Mg, Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging?

AAl and Mg

BZn and Fe

CZn and Pb

DPb and H

EAu and Hg

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Question 29

jamb 1985

If the ONLY pollutants found in the atmosphere over a city are oxides of nitrogen, suspended lead compounds. carbon monoxide and high levels of methane, the probable source(s) of the pollution must be?

Aautomobile exhaust and biological decomposition

Bcombustion of coal and automobile exhaust

Cbiological decomposition only

Dcombustion of coal, automobile exhaust and biological decomposition

Ecombustion of coal and biological decomposition

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Question 30

jamb 1985

What is the formula of sodium gallate if gallium (Ga)shows an oxidation number of + 3?

ANaGaO₃

BNa₂Ga(OH)₃

CNaGa(OH)₃

DNaGa(OH)₄

ENaGaO

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Question 31

jamb 1985

X + Y = Z is an equilibrium reaction. The addition of a catalyst?

Aincrease the amount of Z produced in a given time

Bincreases the rate of change in concentrations of X, Y and Z

Cincreases the rate of disapearance of X and Y

Dincreases the rate of the forward reaction

Edecreases the amounts of X and Y left after the attainment of equilibrium

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