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WAEC questions for "Chemistry :: Rates of Reactions And Equilibrium Systems"
Q1

A catalyst increases the rate of chemical reaction by

A

decreasing the temperature of the reaction

B

decreasing the activation energy of the reaction

C

increasing the surface area of the reactants

D

decreasing the surface area of the products

E
Q2

Which of the following factors will affect the rate of reaction represented by the equation?

2HCl(aq) + CaCO3(s) → CaCl2(aq) + H2O(l) + CO2(g)

I   Pressure 

II  Concentration

III Nature of reactants

IV  Temperature

A

I and II only

B

II, III and IV

C

I, II, III only

D

I, II, III and IV

E
Q3

Consider the equilibrium reaction represented by the equation:

2SO2(g) + O2(g) ↔ 2SO3(g) ΔH = -197kj mol-1. At equilibrium, increase in the total presure of the system brings about

A

decrease in rate of the reaction of the system

B

decrease in temperature of the system

C

increase in concentration of SO3

D

increase in concentration of SO2

E
Q4

Q represents

A

activation energy

B

activation complex

C

enthalpy change

D

heat content of the reaction

E
Q5

Which of the following factors will affect the rate of formation of S(s) in the reaction represented by the equation below?

S2O32-(aq) + 2H+(aq) → SO2(g) + H2O(l) + S(s)

A

Increase in temperature

B

Increase in pressure

C

Removal of H2O3(l)

D

Use of a catalyst

E
Q6

In which of the following reactions is the position of equilibrium not affected by increase in pressure?

A

3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)

B

2NO(g) → N2O4(g)

C

3H2(g) + N2(g) → 2NH3(g)

D

2SO2(g) + O2(g) → 2SO3(g)

E
Q7

Which of the following factors does not affect the rate of reaction of CaCO3 and HCl?

A

Temperature of the reactive

B

Solubility of the CaCO3

C

Concentration of the HCl

D

Surface area of the CaCO3

E
Q8

Consider the reaction represented by the equation below. xNH3(g) + yCl2(g) → zHCl(g) + N2(g). The values of x, y and Z are respectively:

A

2, 4, 6

B

3, 2, 4

C

2, 3, 6

D

3, 2, 6

E
Q9

When ice is changing to water its temperature remains the same because the heat gained is

A

used to seperate the molecules

B

lost partially to atmosphere

C

used to increase the volume of ice

D

less than the activation energy

E
Q10

Which of the following elements will burn in excess oxygen to form a product that is neutral to litmus?

A

Carbon

B

Hydrogen

C

Sulphur

D

Sodium

E
Q11

Which of the following factors that affect the rate of chemical reaction can be explained in terms of the collision theory?

I  Concentration

II  Pressure

III Temperature

IV  Catalyst

 

A

I and II only

B

I, II and III only

C

I and III only

D

I, III and IV only

E
Q12

Which of the following reactions will be affected by change in the pressure at equilibrium?

A

X(g) + Y(g) ↔ W(g) + Z(g)

B

X(g) + 2Y(g) ↔ W(g) + Z(g)

C

2X(g) ↔ W(g) + Z(g)

D

2Y(g) ↔ W(g) + Z(g)

E
Q13

A reducing agent is expected to

A

decolorize acidified KMnO4

B

decolorize acidified FeSO4 solution

C

liberate Cl2 from chloride

D

liberate CO2 from NaHCO3

E
Q14

Why is it necessary to heat the PbBr2? To

A

melt it and make it conduct

B

increase the reaction rate

C

produce electrons which will carry current

D

Vaporize the products at the electrodes

E
Q15

What will happen if more heat is applied to the following system at equilibrium?

X2(g) + 3Y2(g) ↔ 2XY3(g) ; ΔH= -XKj mol-1

A

The yield of XY3 will increase

B

More of XY3 will decompose

C

More of X2 will react

D

The forward reaction will go to completion

E
Q16

Equal amounts of marble chips reacted seperately with 100cm3 of hydrochloric acid of different concentrations. If the marble chips reacted, which of the following remained the same in each case?

A

Average rate of evolution of gas

B

Total mass of gas evolved during the reaction

C

Time taken for the reaction to reach completion

D

Initial reaction rates

E
Q17

Givent that the order of reactivity of four metals is P>Q>R>S, Which of the following reactions is feasible?

A

S + P+ → P + S+

B

Q + S+ → S + Q+

C

R + P+ → P + R+

D

S + Q+ → Q + S+

E
Q18

What is function of H2SO4 in the following reaction?

  conc. H2SO4  
C12H22O11 12C + 11H2O
     

A

Oxidizing agent

B

Strong acid

C

Dehydrating agent

D

Catalyst

E
Q19

Which of the following reactions represents the change that occurs when a photographic film is exposed to sunlight?

A

Ag → Ag+ + e-

B

Ag+ + e- → Ag

C

2Ag + Br2 → 2AgBr

D

Ag+ + Br → AgBr

E
Q20

Chemical equilibrium is attained when

A

reactants in the system are used up

B

concentration of the product are greater than those of the reactant

C

concentrations of the reactants and products remain constant

D

reactants stop forming the production

E
Q21

What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation?

2SO2 + O2 ↔ 2SO2  ΔH = -XKjmol-1

A

Decrease the value of ΔH

B

Increases the collision rate of reactants particles

C

Shifts equilibrium position to the right

D

Reduces the time for attainment of equilibrium

E
Q22

A finely divided form of a metal burns more readily in air than the rod form because the rod has

A

higher molar mass

B

smaller surface area

C

protective oxide coating

D

different chemical properties

E
Q23

Which of the following will displace copper from a solution of copper (II) salt?

A

Aluminium ions

B

Magnesium

C

Silver

D

Zinc ions

E
Q24

What is the value of X in the following equation? Cr2O72- + 14H+ + XO → 2Cr3+ + 7H2O

A

1

B

6

C

8

D

12

E
Q25

Which of the following reactions is feasible?

A

Cl2 + 2KI → 2KCl + I2

B

Cl2 + 2NaF → 2NaCl + F2

C

 Zn + CuCl2 → ZnCl2 + Cu

D

Zn + 2AgNO3 → Zn(NO3)2 + 2Ag

E
Q26

Which of the following lowers the activation energy of a chemical reaction?

A

Freezing mixture

B

Reducing agent

C

Water

D

Catalyst

E
Q27

What will be the effect of increase in pressure on the following system at equilibrium?

2NH3(g) ↔ N2(g) + 3H2(g)

A

Activation energy will decrease

B

The forward reaction will be favoured

C

The concentration of ammonia will increase

D

The reaction will go to completion

E
Q28

Equal voulume of water were added to one mole of each of the folllowing compounds. Which of them produced the largest number of ions?

A

Glucose

B

Sodium trioxonitrate (V)

C

Ethanoic acid

D

Silver chloride

E
Q29

The spontaneity of a chemical reaction is determined by the change in the

A

concentration of the reactants

B

temperature of the system

C

free energy of the system

D

pressure applied to the system

E

volume of the reactants

Q30

A chemical reaction can be made to proceed faster by

I lagging the reaction vessel

II conducting it in abigger vessels

III Grinding the reactant(s) if solid

IV increasing the reaction temperature

A

IV

B

I and II

C

III and IV

D

I, II and III

E

I, II, III and IV

Q31

From the following equations, what is the order of decreasing reactivity of X, Y and Z?

Y(s) + X2+(aq) → Y2+(aq) + X(s), X(s) + Z2+(aq) → X2+(aq) + Z(s)

A

X>Y>Z

B

Y>X>Z

C

Z>Y>X

D

Y>Z>X

E

X>Z>Y

Q32
The position of equilibrium in a reversible reaction is affected by
A
particle size of the reactants
B
change in the concentration of reactants
C
change in size of the reaction vessel
D
vigorous stirring of the reaction mixture
E
presence of a catalyst
Q33

Which of the following substances labelled P to V in the equation below would be left on the filter paper if the reaction mixture were filtered? P(aq) + Q(aq) → V(s) + R(aq) + T(g)

A

P

B

Q

C

V

D

T

E

R

Q34

In which of the processes represented by the following equations will the rate be affected by the surface area of the starting materials?

I Zn(s) + H2SO4(aq) → ZnSO4 + H2(g) + NaCl(aq)

II

  H2O  
NaCl(s)  →  NaCl(aq)
     

III NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

IV Ca(OH)2(aq) + CO2(g) → CaCO3(S) + H2(l)

A

IV

B

I and II

C

III and IV

D

I, II and III

E

I, II, III and IV

Q35

Which of the following equations represents a neutralization reaction?

A

CaOCl2 + 2HCl → Cl2 + CaCl2 + H2O

B

Na2O2 + H2SO4 → Na2SO4 + H2O2

C

H2SO4 + KOH → KHSO4 + H2O

D

2Na + 2H2O → 2NaOH + H2

E

CuSO4 +2NaOH → Cu(OH)2 + Na2SO4 

Q36
which of the following statements is not correct about catalyst? It
A
remains unchanged chemically at the end of a reaction
B
helps to establish equilibrium faster in the reversible reaction
C
can start a chemical reaction which will normally not take place
D
is usually specific in its action
E
alters the rate of chemical reaction
Q37

Which of the following reactions at equibilibrium will by affected by an increase in pressure?

I N2(g) + 3H2(g) → 2NH3(g)

II 2SO2(g) + O2(g) → 2NO(g)

III N2(g) + O2(g) 2NO(g)

IV CO4(g) + H2O → CO2(g) + H2(g)

A

IV

B

I and II

C

III and IV

D

I, II and III

E

I, II, III and IV

Q38
Which of the following statement is/are correct about catalysts? They I alter the rate of chemical reactions II are generally specific in action III remain unchanged chemically at the end of the reaction IV shift the equilibrium position in a reversible reaction
A
IV
B
I and II
C
III and IV
D
I, II and III
E
I, II, III and IV
Q39

Which of the following statement is correct about the following system at equilibrium?

PCl5(g) ↔ PCl3(g) + Cl2(g) ; ΔH positive

A

Increase in temperature increases the yield of PCl5

B

PCl5(g) is less stable at high pressures

C

The concentrations of PCl3 and Cl2 increase at higher pressure

D

Decrease in temperature favours forward reaction

E

Decrease in pressure favours forward reaction

Q40

Which of the following would increase the rate of reaction of chips of metal M as shown in the equation below?

M(s) + 2Hcl(aq) → MCl2(aq) + H2(g)

A

Dilute the hydrchloric acid

B

Adding some distilled water

C

Decreasing the temperature

D

Grinding the metal into powder

E

Increasing the pressure

Q41

In a chemical reaction, the reacting species possess energy of motion known as

A

potential energy

B

free energy

C

bond energy

D

kinetic energy

E

hydration energy

Q42

Which of the following reations is accompanied by the first ionization energy of an element X?

A

X+(aq)  X2+(aq) + e-

B

X-(g)   X(g) + e-

C

X+(g)  X2+(g) + e- 

D

X(g)  X+(g) + e-

E

X(s) X+(g) + e-

Q43

Which of the following equations illustrate(s) substition reaction?

I. 2CH3CH2OH + 2Na → 2CH3CH2ONa + H2

II. C6H6 + HNO3 → C6H5NO2 + H2O

III. CH3CH2OH + HBr → CH3CH2Br + H2O

IV CH4 + Cl2 → CH3Cl + HCl

A

IV

B

I and II

C

III and IV

D

I, II and III

E

I, II, III and IV

Q44

Consider the reaction represented by the following equation:

CaCl2(aq) + H2C2O4(aq) ↔ CaC2O4(s) + 2HCl(aq). Which of the following would dissolve the precipitate of CaC2O4 formed?

A

Stirring the mixture vigorously

B

Adding more calcium chloride solution

C

Increasing the concentration of the ethanedoic acid

D

Adding concentrated hydrochloric acid

E

Adding some distilled water

Q45

Sturdy the reaction represennted by the equation below:

2H2O(l) → O2(g) + 2H2O(l). Which of the following will not increase the reaction rate?

A

Heating the hydrogen peroxide

B

Adding a pinch of MnO2 to the reactant

C

Increasing the concentration of H2O2

D

Adding water to the reactants

E

Exposing the reactants to sunlight

Q46

Which of the following processes is a physical reaction?

A

Electrolysis

B

Hydrolysis

C

Allotropic change

D

Neutralization

E

Corrosion

Q47

"The rate of reaction is proportional to the number of effective collision occurring per second between the reactants" this statement is associated with the

A

kinetic theory

B

rate law

C

atomic theory

D

collision theory

E

gas laws

 

Q48

What is the value of n in the following equation? XO4 + 8H+ + ne- → X2+ + 4H2O

A

2

B

3

C

4

D

5

E

6

Q49

Which of the following statement is/are correct of the compound with the formular K4Fe(CN)6?

I Its IUPAC name is potassium hexacyanoferrate (II).

II It has six ligands

III It is a complex salt of a transition metalsolut.

IV Its solution gives a green precipitates with aqueous sodium hydroxide

 

A

IV

B

I and III

C

III and IV

D

I, II, and III

E

I, II, III and IV

Q50

The factors that affect the rate of chemical reactions inlcude

I concentration

II temperature

III presence of catalyst

IV collision frequency of particles

A

IV

B

I and III

C

III and IV

D

I, II and III

E

I, II,  III and IV

Q51

When starch undergoes complete enzyme-catalyzed hydrolysis, the resulting product is

A

glucose

B

maltose

C

sucrose

D

fructose

E

cellulose

Q52

Which of the reactions represented by the following equations will take place at room temperature?

A

C + H2O → CO + H2

B

CuO + H2 → Cu + H2O

C

N2 + 3H2 → 2NH3

D

2Na + 2H2O → 2NaOH +H2

E

2Fe + 3Cl2 → 2FeCl2

Q53

  MnO2  
2KClO3  → 2KCl + 3O2
  heat  
In the reaction represented by the equation above, the fuction of MnO2 is to

A

Increase the surface area of the reactants

B

Increase hte concentration of oxygen compounds present

C

Increase the change in free energy of the system

D

decrease the activation energy of the process

E

decrease the surface area of the product

Q54

Which of the following is/are correct about equilibrium?

I Chemical equilibrium is attained when rates of forward and backward reactions are equal

II Changes in concentration of reactants will alter equilibrium position

III A catalyst alters equally the rate of both the forward and backward reaction

IV Temperature affects equilibrium concentration

A

IV

B

I and III

C

III and IV

D

I, II and III

E

I, II, III and IV

Q55

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

A

Zn(s) + 2Hcl(aq) → Zncl2(aq) + H2(g)

B

Fe(s) + H2So4(aq) → FeSO4(aq) + H2(g)

C

Cu(s) + 2HCl(aq) → CUCl2(aq) + H2(aq)

D

2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) 

E

Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2 

Q56

A catalyst which increase the rate of a chemical reaction does so by

A

Increasing the reaction pathway

B

Increasing the surface area of reacts

C

Increasing the pressure in the system

D

Decreasing the temperature at which reaction occurs

E

Decreasing the activation energy of the reaction

Q57

Which of the following is a condition for a spontaneous reaction?

A

ΔH - TΔS is zero

B

ΔH - TΔS is positive

C

ΔH - TΔS is negative

D

ΔS is zero

E

ΔS is positive

Q58

Which of the following can be used to illustrate brownian motion?

I suspension of sulphur in water viewed under microscope
II smoke in a glass container illuminated by a strong light from the sides
III A dusty room being swept and viewed through a beam of sunlight
IV Boiled distilled water viewed under sunlight

A

IV

B

I and III

C

III and IV

D

I, II, and III

E

I, II, III and IV

Q59

Which of the following properties is/are not exhibited by catalyst?

I Altering the rate of chemical reaction
II Same mass and composition at the end of reaction
III Causing a change in the equilibrium position of a reversible reaction
IV Starting off a reaction which will normally not occur

A

IV

B

I and III

C

III and IV

D

I, II and III

E

I, II, III and IV

Q60
Equilibrium is said to be attained in a reversible reaction when
A
all the reactants have been used up
B
all the products have been formed
C
There is no further change in temperature
D
The rate of formation of the products decrease with time
E