CHEMISTRY PAST QUESTIONS AND ANSWERS

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SSCE/NECO/GCE (CHEMISTRY PAST QUESTIONS)

CHEMISTRY PAST QUESTIONS

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1 / 60

Category: CHEMISTRY PAST QUESTIONS

Substances which absorb water from the atmosphere without dissolving in it are said to be

insolube

anhydrous

hydrated

hygroscopic

2 / 60

Category: CHEMISTRY PAST QUESTIONS

How many electrons are removed from Cr^2- when it is oxidized to CrO₄^2-?

3 / 60

Category: CHEMISTRY PAST QUESTIONS

The crystal layers in graphite are held together by

electrostatic forces

covalent bonds

van der Waals' forces

hydrogen bonds

4 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following compounds dissolves in water to give an alkaline solution?

Sodium chloride

Sulphur (IV) oxide

Potassium oxide

Ammonium chloride

5 / 60

Category: CHEMISTRY PAST QUESTIONS

What is the value of x in the following equation? Cr₂O₇^2- + 14H⁺ + xe- → 2Cr³⁺ + 7H₂O

6 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following movements can be described as random motion?

gas molecules colliding in a flask

wheelbarrow being pushed

car travelling on a straight line

planets going round the sun

7 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following contains co-ordinate covalent bond?

NH4

HCI

Na+CI

CH4

8 / 60

Category: CHEMISTRY PAST QUESTIONS

Dehydration of ethanol produces

propan-1,2,3-triol

ethanoic acid

ethanal

ethene

9 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following substances decomposes when an electric current is passed through it?

Hydrochloric acid

Zinc rod

Glucose solution

Tetrachlormethane

10 / 60

Category: CHEMISTRY PAST QUESTIONS

Helium is preferred to hydrogen in filling balloons because hydrogen

exhibits isotopy

is a component of water

is inflammable

is diatomic

11 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following features of a human skeleton can be determined by carbon-dating?

Height

Age

Race

Mass

12 / 60

Category: CHEMISTRY PAST QUESTIONS

The atoms of four elements are represented as ₂₀Q, ₁₆R, ₁₀S and ₈T Which of the elements would be unreactive?

13 / 60

Category: CHEMISTRY PAST QUESTIONS

If the solubility of KHCO₃ is 0.40 mole dm^-3

100.0g

10.0g

4.0g

40.0g

14 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?

Both electrodes gain electrons

The blue colour of the solution fades gradually

The cathode becomes coated with copper

The anode increases in mass

15 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following pairs of reagents recat to produce hydrogen?

Zinc and concentrated trioxonitrate (V) acid

Water and calcium dicarbide

Magnesium and dilute tetraoxosulphate (VI) acid

Copper and dilute hydrochloric acid

16 / 60

Category: CHEMISTRY PAST QUESTIONS

What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO₂ + O₂ ⇌ 2SO₃; ∆H = - xKJmol-¹

Reduces the time for attainment of equilibrium

Increases the collision rate of reactant particles

Decreases the value of ∆H

Shifts equilibrium position to the right

17 / 60

Category: CHEMISTRY PAST QUESTIONS

Chlorine atom forms CI by

Losing one electron

Gaining one electron

Donating lone pair of electrons

Sharing one electron

18 / 60

Category: CHEMISTRY PAST QUESTIONS

Pauli Exclusion Principle is related to

reversiblility of equlibrium reactions

electronegativity values of elements

collision theory of reaction rates

quantum numbers of electrons

19 / 60

Category: CHEMISTRY PAST QUESTIONS

Equal volumes of CO₂ cnd CO at s.t.p have the same

number of molecules

density

mass

rate of diffusion

20 / 60

Category: CHEMISTRY PAST QUESTIONS

What type of reaction is involved when wood shavings produce a brown gas with concentrated HNO₃?

Dehydration

Redox reaction

Nutralization

Destructive distillation

21 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the orbitals 4s, 4p, 4d and 4f has the lowest energy?

22 / 60

Category: CHEMISTRY PAST QUESTIONS

What is the function of sulphur (IV) oxide in the reaction represented by the following equation? SO _2(aq) + 2H₂S_(g) → 3S _(s) + 2H ₂O _(l)

Dehydrating agent

Bleaching agent

Acid

Oxidising agent

23 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following occurs when a solution of CuSO₄ is electrolysed using copper electrodes?

The blue colour of the solution fades gradually

The cathode becomes coated with copper

The anode increases in mass

Both electrodes gain electrons

24 / 60

Category: CHEMISTRY PAST QUESTIONS

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

free energy of the system

pressure applied to the system

temperature of the system

concentration of the reactants

25 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following increases as boiling water changes to steam?

degree of disorder in the system

number of molecules

activation energy

temperature of the system

26 / 60

Category: CHEMISTRY PAST QUESTIONS

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

Magnesium

Zinc ions

Aluminium ions

Silver

27 / 60

Category: CHEMISTRY PAST QUESTIONS

30cm³ pf hydrogen at s.t.p combine with 20cm³ of oxygen to form steam according to the following equation 2H_2(g) + O_2(g) → 2H₂O_(g). Calculate the total volume of the gaseous mixture at the end of the reaction

30cm cube

50cm cube

25cm cube

35cm cube

28 / 60

Category: CHEMISTRY PAST QUESTIONS

An exothermic reaction is one which involves

loss of heat to the surrounding

evolution of gas as it proceeds

positive change in value of enthalpy

attainment of dynamic equilibrium

29 / 60

Category: CHEMISTRY PAST QUESTIONS

What mass of copper would be deposited by a current of 1. 0 ampere passing for 965 seconds through copper (ll) tetraoxosulphate (IV) solution? [Cu = 63.5; 1F = 96500C]

0.318g

18g

6.35g

0.635g

30 / 60

Category: CHEMISTRY PAST QUESTIONS

What is the oxidation number of nitrogen in AI(NO₃)₃?

+ 3

+ 6

+ 5

+ 1

31 / 60

Category: CHEMISTRY PAST QUESTIONS

A concentrated solution containing H⁺, Cu²⁺,OH^- and CI^- was electrolysed using platiunm electrodes which of the ions will be discharged at the cathods?

H+

Cu2+

OH-

CI-

32 / 60

Category: CHEMISTRY PAST QUESTIONS

What will be the effect of increase in pressure on the following system at equilibrium? 2NH_2(g) N_2(g) + 3H_2(g)

the concentration of ammonia will increase

Activation energy will decrease

the forward reaction will be favoured

the reaction will go to completion

33 / 60

Category: CHEMISTRY PAST QUESTIONS

Electrovalent compounds are characterized by

high melting point

strong oxidizing ability

solubility in ethanol

high molar mass

34 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following methods is suitable for the preparation of an insoluble salt?

Neutralisation

Action of an acid on a metal

Double decomposition

Action of an acid on a trioxocarbonate (IV)

35 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following can undergo both addition reactions and substitution reactions?

Propene

Hexane

Benzene

Pentane

36 / 60

Category: CHEMISTRY PAST QUESTIONS

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

Q + S+ → S + Q+

S + P+ → P + S +

R + P+ → P + R+

S + Q+ → Q + S+

37 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following compounds dissolves in water to form a solution with pH below 7?

Ammonium chloride

Potassium hydroxide

Sodium trioxocarbonate (IV)

Sodium tetraoxosulphate (VI)

38 / 60

Category: CHEMISTRY PAST QUESTIONS

Petrol consists mainly of

hydrocarbons

alktanols

polymers

alkanoates

39 / 60

Category: CHEMISTRY PAST QUESTIONS

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

Catalyst

Water

Freezing mixture

Reducing agent

40 / 60

Category: CHEMISTRY PAST QUESTIONS

The type of chemical bond that exists between potassium and oxygen in potassium oxide is

metallic

covalent

dative

ionic

41 / 60

Category: CHEMISTRY PAST QUESTIONS

The presence of unpaired electrons in an atom of a transition metal gives rise to

ductility

paramagnetism

shiny appearance

nalleability

42 / 60

Category: CHEMISTRY PAST QUESTIONS

Aluminium is extracted from

magnetite

cryolite

cassiterite

bauxite

43 / 60

Category: CHEMISTRY PAST QUESTIONS

Pipe-borne water is usually chlorinated in order to

remove the hardness in the water clear

kill harmful bacteria in the water

coagulate sediments in the water

improve the teste of the water

44 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following properties increases down a group in the Periodic Table?

Electon affinity

Ionization energy

Atomic radius

Electronegativity

45 / 60

Category: CHEMISTRY PAST QUESTIONS

The gas evolved when dilute tetraoxosulphate (VI) acid reacts with sodium hydrogen trioxocarbonate (IV) is

sulphur (VI) oxide

oxygen

hydrogen

carbon (IV) oxide

46 / 60

Category: CHEMISTRY PAST QUESTIONS

Elactrostatic force of attraction between sodium ion and halide ion is greatest in

NaF

NaBr

NaI

NaCI

47 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following will produce oxygen and hydrogen during its electrolysis using platinum electrode?

Glucose solution

Aqueous copper (ll) tetraoxosulphate (IV)

Concentrated hydrochloric acid

Dilute sodium chloride solution

48 / 60

Category: CHEMISTRY PAST QUESTIONS

Elements which belong to the same group in the Periodic Table are characterized by

difference of +1 in the oxidation numbers of successive members

presence of the same number of electron shells in the respective atoms

difference of 14 atomic mass units between successive members

presence of the same number of outermost electrons in the respective atoms

49 / 60

Category: CHEMISTRY PAST QUESTIONS

What is responsible for metallic bonding?

Attraction between positive and negative ions

Sharing of electrons between the metal atoms

Attraction between the atomic unclei and cloud of electrons

transfer of electrons from one atom to another

50 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following would dissolve in warm dilute H₂SO₄ without effervescence, to give a blue solution?

Copper (ll) trioxocarbonate (IV)

Copper turnings

Copper (ll) oxide

Copper alloy

51 / 60

Category: CHEMISTRY PAST QUESTIONS

A radioactive solid is best stored

in a cool, dark cupboard

in a box lined with lead

under paraffin oil

under ultraviolet light

52 / 60

Category: CHEMISTRY PAST QUESTIONS

Exhaust fumes discharged from a smoky vehicle gradually become invisible as a result of

combustion

emission

absorption

diffusion

53 / 60

Category: CHEMISTRY PAST QUESTIONS

A mixture of calcium chloride and calcium trioxocarbonate (IV) in water can be separated by

sublimation

filtration

evaporation

distillation

54 / 60

Category: CHEMISTRY PAST QUESTIONS

What is oxidized in the reaction represented by the following equation? 3CU + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O

Hydrogen

Nitrogen

Copper

Oxygen

55 / 60

Category: CHEMISTRY PAST QUESTIONS

It can be concluded that gastric juice

contains enzymes

has pH value of 7

is a mixture

is acidic

56 / 60

Category: CHEMISTRY PAST QUESTIONS

What is the shape of a molecule of CCI₄?

Linear

Trigonal planar

Pyramidal

Tetrahedral

57 / 60

Category: CHEMISTRY PAST QUESTIONS

P _Total = F₁ + P₂ + P ₃ + .........P_n' where P _Total is the pressure of a mixture of gasses. The equation above is an expression of

Gay-Lussac's Law

Dalton's law

Graham's law

Boyle's law

58 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following statements about ideal gases is/are correct?

I. The cohesive forces between their particles are negligible

ll. The have no definite volume but occupy the volume of their containers

III. They are not compressible

IV. Their particles collide with loss of energy

l, ll and lll only

l, ll, lll, and IV

l and ll only

l only

59 / 60

Category: CHEMISTRY PAST QUESTIONS

Two radioactive elements Q and S have half-life periods of 10 hours and 20 hours respectively. Therefore

Q is twice as stable as S

Q emits fewer particles than S

S decays faster than Q

S is more stable than Q

60 / 60

Category: CHEMISTRY PAST QUESTIONS

Which of the following is not correct about oxidation number convention? The oxidation number of a/an

atom of a diatomic molecules is + 2

element in the free state is zero

alkali meta like sodium in its compounds is + 1

monatomic ion is equal to its charge

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