WAEC GCE Chemistry Questions and Answers 2020/2021 (Essay and Objectives)

WAEC GCE Chemistry Questions and Answers 2020Welcome to 2020 WAEC Chemistry questions and Answers. You will find WAEC GCE Chemistry Objective Answers, WAEC Chemistry Essay 2020, WAEC GCE 2020 Chemistry and the tips you need to pass your WAEC GCE Chemistry examination at ease.

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WAEC GCE Chemistry Questions and Answers 2020 (Expo)

The 2020 WAEC GCE Chemistry expo will be posted here today, 3rd December during the WAEC GCE Chemistry examination. Keep checking and reloading this page for the answers.

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Today’s WAEC GCE Chemistry OBJ Answers:

NOTE: Pls Trace It From Your Objective.
[If you see any options here pick it from your objectives]

1 Involves the loss and gain of electrons
2 Polymerisation
3 Global warming
4 3
5 Zinc ions
6 +1.56V
7 Ethene
8 NH3
9 Propanol
10 28
11 Hydrolysis
12 d-orbital
13 Lowering the activation energy
14 Closeness between reactant particles
15 Remaining the same with time
16 Reaction vessel Fels cool during the reaction
17 Faster
18 Solvent extraction
19 Saturated Solution
20 2.75mol/dm³
21 Partially dissociates in aqueous solution
22 138g
23 HI
24 2.00cm³
25 hydrogen chloride
26 strong electrovalent bond between ions
27 is not ductile
28 Electrons
29 C2H4
30 Aluminium
31 0.010mol/dm³
32 PbCO3
33 Linear
34 HCL and HOCL
35 +1
36 Ionic bond
37 have relatively low ionization energy
38 sour to taste
39 I,III and IV only
40 chrometography
41 2.00 dm
42 mole of solvent in 1dm³ of solution
43 does not contain neutron
44 1s²2s²2p⁶
45 Ammonium chloride
46 IV
47 I,II and IV only
48 Quantum numbers of Electrons
49 -273⁰C
50 Mass number

1-10: DDDADBBABA

11-20: CDABDCCDDC

21-30: ACDBDCCDAB

31-40: BCADABDBAC

41-50: ABB

More Answers loading…

WAEC GCE Chemistry Theory Answers:

(1a)

(i) Sodium trioxonitrate (v) decahydrate

NaNO₃ . 10H₂O

(ii) Sodium Oxide –> Na₂O

(iii) Potassium tetraoxophospate (v) –> K₃PO₄

(1b)

Products formed are:

Hydrogen gas (a+ cathode)

Chlorine gas (a+ anode)

(1ci)

it decrease down the group

(1cii)

As the atomic radius increases down the group the attraction of the positive nucleus of the electron outer most electron, thus the ionization energy decreases

(1di)

Nitrogen and carbon (ii) oxide

(1dii)

it is used to heat furnace

(1diii)

it is a source of nitrogen for the manufacture of ammonia

(1ei)

Sodium hydrogen – used in qualitative analysis

– Purification of bauxite

(1eii)

Sodium trioxocarbonate (iv)

-Manufacture of glass

-As a water soften

(1j)

2-amino propane

(2ai)
Percentage C5H12 of mass m = 7.2g
Volume of O2 = 20.0dm³
(i) from the general combustion equation
CxHy(g) + (x+y/4)O2 –> XCO2 + y/2H2O
C5H12(l) + 802(g) –> 5CO2(g) + 6H2O(l)

(2aii)
1 mole of C5H12(72g) = 5 moles of CO2
At stop 7.2gC5H12 = x volume of CO2
X = 7.2g×5×22.4dm³/72g
X = 5×2.224 = 11.2dm³ of CO2

(2aiii)
Volume of oxygen left after the reaction from the equation of reaction
1 mole of C5H12(72g) = 8(22.4)dm³
7.2g = x
X = 7.2×8×22.4/72 = 17.92dm³
Volume of O2 left after the reaction
= 20.0dm³ – 17.92dm³
= 2.08dm³

(2b)
When molecules collide with one another they possess kinetic energy. As most energetic molecules (those with greater kinetic energy) try to escape. Their escape may be facilitated by heat or by passing a wave of air over the container or by increasing the surface area of the container. As they try to do this, some molecules will loose energy on collision and fall back to the container; as such the average kinetic of the molecules of the liquid in the container reduces which results to cooling effect.

(2ci)
Avogadro’s Law states that the total number of atoms/molecules of a gas (i.e. the amount of gaseous substance) is directly proportional to the volume occupied by the gas at constant temperature and pressure.

(2cii)
N2(g) + 3H2—> 2NH3
Where 1 mole = 30cm³ of gas

At constant temperature, the volume of a fixed mass of gas. When the volume of a cylinder or a container is increased, the gases have more space to travel and collide hence the pressure is reduced but as the volume is decreased or compressed the gases have less space to travel therefore more pressure is built up.

No (3ai)
¹³R, ⁸Q
¹³R=1s²,2s²,2p⁶,3s²,3p¹
⁸Q=1s²,2s²,2p⁴

(3aii)
¹³R=2,8,3
Valency of ¹³R is 3
⁸Q= 2,6
Valency of ⁸Q=2

(3di)
2H² SO4(aq)+4NaOH(aq)—>2Na² SO4(aq)+4H²O(s)

(3dii)
Sodium teraoxosulphate (iv) salt and water

(3diii)
The resulting solution NaSO4 is basic and will have no effect on litmus paper

(3div)
When heated to dryness it can be used as a dehydrating agent

(3di)
2H² SO4(aq)+4NaOH(aq)—>2Na² SO4(aq)+4H²O(s)

(3dii)
Sodium teraoxosulphate (iv) salt and water

(3diii)
The resulting solution NaSO4 is basic and will have no effect on litmus paper

(3div)
When heated to dryness it can be used as a dehydrating agent

Typing….

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The questions below are strictly for practice.

1. Which of the following statements best explains the difference between a gas and a vapour?

(a) Unlike gases, vapours are liquids at room temperature

(b) Unlike gases, vapour can easily be condensed into liquids

(c) Unlike gases, vapour is readily converted into solids

(d) Vapours are generally denser than gases

2. Consider the following reaction equation: 2HCI + Ca(OH)2 → CaCI2 + H2O. what is the volume of 0.1 moldm-3, HCI that would completely neutralize 25cm3 or 0.3 moldm-3 Ca(OH)2?

(a) 150 cm3

(b) 75 cm3

(c) 30 cm3

(d) 25 cm3

 3. Cu and HNO3 are not suitable for preparing hydrogen gas because of their

(a) Reactivity and oxidation respectively

(b) conductivity and corrosiveness respectively

(c) melting point and reduction respectively

(d) electronegativity and solubility respectively

4. Which of the following formulae cannot be an empirical formula?

(a) CH

(b) CH2

(c) P2O5

(d) N2O4

5. One of the criteria for confirming the purity of benzene is to determine its

(a) Heat capacity

(b) boiling point

(c) mass

(d) colour

6. When chlorine is passed through a sample of water, the pH of the water sample would be (a) <7

(b) >7

(c) = 7

(d) 0

7. How many atoms are contained in 0.2 moles of nitrogen [N = 6.02 x 1023]

(a) 1.20 x 1023

(b) 2.41 x 1023

(c) 3.62 x 1023

(d) 4.82 x 1023

8. The strength of metallic bonds depends on the

(a) charge density of the atoms

(b) ductility of the metal

(c) number of valence electrons

(d) total number of electrons in the atoms

9. When zinc is added to AgNO3 solution, crystals of silver forms on the zinc surface. This indicates that zinc is

(a) oxidized

(b) reduced

(c) decomposed

(d) dissociated

10. The empirical formula of a compound containing 0.067 mol Cu and 0.066 mol O is [Cu = 63.5, O = 16.0]

(a) Cu2O

(b) CuO

(c) CuO2

(d) Cu2O2

See:

11. The change in the oxidation state of iron in the reaction represented by the equation below is 2FeCI3 + H2S →2FeCI2 + 2HCI + S

(a) +2 to +3

(b) +3 to +2

(c) 0 to +2

(d) +3 to 0

12. Which of the following methods can be used to separate blood cells from plasma?

(a) Centrifugation

(b) Filtration

(c) Chromatography

(d) Distillation

13. Which of the following statements about ionic radius is correct? ‘Ionic radius

(a) Increases as nuclear charge increases

(b) decreases as nuclear charge increases

(c) decreases as nuclear charges decreases.

(d) remains constant as nuclear charge increases

14. Analysis of a hydrocarbon shows that it contains 0.93 g of carbon per gram of the compound. The mole  ratio of carbon to hydrogen in the compound is [H=1.0, C=12.0]

(a) 1:1

(b) 1:2

(c) 2:1

(d) 2:3

15. The law of definite proportions states that

(a) pure samples of same compound contain the same elements combined in the same proportion by mass

(b) pure samples of substances are in the same proportion by mass

(c) chemical compounds are pure because they contain the same elements

(d) matter can neither be created nor destroyed

16. What is the relative molecular mass of a compound which has empirical formula CH2O? [H=1.0, C=12.0,0=16.0]

(a) 42

(b) 45

(c) 126

(d) 180

17. Atoms are electrically neutral because they

(a) don not conduct electricity

(b) contain equal number of protons and electrons

(c) are composed of neutrons and electrons

(d) cannot be attracted by electromagnetic field

18. Common salt (NaC1) is used for preserving foods. Which of the following properties could be used to determine its purity before use?

(a) Solubility in water

(b) melting point

(c) Relative density

(d) Crystalline nature

19. Which of the following electron configurations represents the transition element chromium (24Cr)?

(a) 1s2 2s2 2p6 3s2 3p6 4s2 3d4

(b) 1s22 2s2 2p6 3s2 3p6 3d6

(c) 1s2 2s2 2p6 2s2 3d4 4s1 (d) 1s2 2s2 2p6 3s2 3p6 4s1 3d5

20. The atomic number of an isotope of hydrogen is equal to its mass number because it

(a) has a totally filled valence shell

(b) has a high charge to mass ratio

(c) does not contain neutrons (d) exhibits isotopy

21. The total number of shared pair of electrons in the compound below is

(a) 5

(b) 6

(c) 10

(d) 12

22. The bonding pair of electrons in a hydrogen chloride molecule is pulled towards the chlorine atom because

(a) Chlorine has a larger atomic size

(b) chlorine has a large atomic mass

(c) chlorine is more electronegative

(d) there is no bonding orbitals within the hydrogen atom

23. The solubility of CO2 in water can be accounted for by

(a) van der waal’s forces

(b) ionic attraction

(c) dipole attraction

(d) covalent bonding

24. Which of the following properties would not influence electrovalent bond information?

(a) Electronegativity

(b) Electron affinity

(c) Ionization potential

(d) Catalytic ability

25. Particles in a solid exhibit

(a) Vibrational motion only

(b) vibrational and translational motion

(c) vibrational and random motion

(d) random and translational motion

WAEC GCE Chemistry Essay 2020

The above questions are not exactly 2020 WAEC Chemistry questions and answers but likely WAEC Physics repeated questions and answers.

These questions are for practice. The 2020 WAEC GCE Chemistry expo will be posted on this page 30 minutes before the WAEC GCE Chemistry examination starts. Keep checking and refreshing this page for the answers.

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If you have any questions about the WAEC GCE Chemistry questions and answers, kindly drop your question in the comment box.

Last Updated on December 3, 2020 by Admin

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