Waec Chemistry Answers 2022 for 8th June 2022

Waec Chemistry Answers 2022: Welcome to the Expobite answer page where you will get verified and 100% authentic and correct Waec Chemistry Answers 2022 for Wednesday 8th June 2022 both objective and essay (theory).

Wednesday, 8th June 2022

  • Chemistry 2 (Essay) 2:00pm – 4:00pm
  • Chemistry 1 (Objective) 4:00pm – 5:00pm

: CHEMISTRY 

==> Chemistry+Obj!
1ABACCABBCD
11DCDBCCDCDB
21BDCADAABCA
31CBDCCDCBBD
41CACCCDADCA

CHEMISTRY
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(1ai)
According to Lewis, an acid can be defined as a substance that can accept a pair of non-bonding electrons i.e an electron pair acceptor.

(1aii)
AlCl₃

(1b)
Salting out is a process through which soap is precipitated as solid from the suspension by adding common salt to the suspension. It is a purification process.

(1c)
Reagent – Silver trioxonitrate(v)
Condition – The reaction takes place at high temperatures and pressure.

(1d)
This is the proportion at which isotopes of an element are to each other in its composition.

(1e)
(i) It has a stable configuration
(ii) This is because they have a covalent bond.

(1f)
They can be differentiated using barium chloride. When barium chloride is added to concentrated H₂SO₄ a white precipitate is formed with concentrated HNO₃

(1g)
[TABULATE]

-ELECTROCHEMICAL CELL-
(i) There are two electrolytes
(ii) Salt bridge is present.

-ELECTROLYTIC CELL-
(i) There is only one electrolyte
(ii) There is no salt bridge present.

(1h)
The lower the ionisation energy, the higher the reactivity of metals. Since it decreases down the group, the reactivity increases down the group I.

(1i)
This can be defined as a formula that shows the actual number of atoms in a compound.

(1j)
(i) NH₃
(ii) This is because its interaction is perfectly inelastic.

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(2ai)
Ionization energy can be defined as the energy required to remove a loosely bound electron from the outermost shell of a gaseous covalently bonded atom.

(2aii)
This is because B has more shells than Be which makes the valence electrons to be far from the nucleus making it require less energy due to lesser nuclear attraction.

(2b)
I = 0.12A, t = 500seconds
m = 0.015g, F =96500C
M = 48.0, Charge = ?
Using;
m = MIt/CF
C = MIt/mF
C = (48×0.12×500)/(0.015×96500)
C = 2

(2ci)
Al₂O₃

(2cii)
(i) Electricity supply
(ii) Nearness to source of material

(2di)
This can be defined as a property of metal which are weakly attracted to an applied magnetic field

(2dii)
(i) I → ₂₄Cr²⁺ → 2
₂₄Cr⁶⁺ → 0

(ii) ₂₄Cr²⁺

(iii) It has unpaired electrons.
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(3ai)
This can be defined as the number of atoms or molecules in one mole of a substance which is equal to 6.02 ×10²³

(3aii)
Mass/m.m = no. of molecules/Avogadro’s number
(2.30/m.m) × (3.01×10²²/6.02×10²³)
m.m = (2.30×6.02×10²³)/3.01×10²²
m.m = 46g/mol

(3aiii)
Since the molar mass = 46g/mol
The formula is NO₂
:. 14+(16×2)
14+32 = 46g/mol
:. NO₂

(3bi)
(i) There is no reaction but rather forms a layer underneath the water
(ii) It reacts violently with water forming white silicon dioxide and hydrogen chloride gas.

(3bii)
The reaction is different because CCl₄ is an organic substance while SiCl₄ is not.

(3ci)
Extraction of copper

(3cii)
(i) CuSO₄
(ii) CuCl₂

(3ciii)
Cu²⁺ + 2e⁻ —> Cu

(3civ)
Using; m = ZIt
Z = m/It
Z = 3.2/(50x(3×60)+13)
Z = 3.2/(50×193)
Z = 3.2/9650
Z = 0.000332g/Asec

(3d)
https://i.imgur.com/wnfOVYP.jpg.

Oxygen can be prepared by heating KClO₃ in the presence of manganese(iv)oxide which acts as a catalyst to produce KCl and oxygen gas. The reaction takes place at a lower temperature and much faster rate.
KClO₃ (MnO₂)heat—–> KCl + O₂
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(5a)
(i) It melts to clear mobile liquid
(ii) A brownish gas is evolved.

(5bi)
(i) Carbon(ii)oxide
(ii) Lead(ii)oxide

(5bii)
Methane(CH₄)

(5biii)
(i) It leads to erosion
(ii) It causes pollution

(5biv)
This is because it has more surface area than it occupies leading to a faster rate of reaction.

(5bv)
Ammoniacal liquor

(5ci)
When water is added to white anhydrous CuSO₄ it turns blue.

(5cii)
(i) It removes the hardness by precipitating the trioxocarbonate(iv)

(ii) It removes the hardness by removing the calcium or magnesium ion and precipitating trioxocarbonate(iv).

(5ciii)
Ca(HCO₃)₂ → CaCO₃ + H₂O + CO₂

Examkey.net Chemistry pin questions and answers for today, examkey, joberplanet, lasu-info, ceebook, noniwap, noniexpo, examspot, unn-edu, nairaland, utmeofficial, bestexamportal

WAEC 2022 Chemistry Questions & Answers [AUTHENTIC]

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How to Pass Waec Chemistry 2022 Examination

  1. Ask your instructor for an exam outline and what to expect on the exam.
  2. Create an overview. Review your notes and any assignments you had.
  3. Review the course’s main ideas.
  4. For each big idea, review its sub-topics and supporting details.
  5. Practice. Use old exams to get a feel for the style of questions you might be asked.

Hints

  • Be realistic. No one can study for 8 hours a day.
  • Make sure you get plenty of food, sleep, and relaxation.
  • Try to study in the same place at the same time every day.
  • At the beginning of each study, period review the last thing you studied for 10 minutes.
  • Rewrite your notes. It can help you retain information.
  • Read your notes out loud.
  • If you don’t complete a particular task, don’t worry just carry it over to your next session.
  • Don’t simply memorize facts. Ask yourself broad open-ended questions about the material that’s been covered.

The Night Before the Exam

  1. Sleep!
  2. Try to stick to the review. Don’t try to learn anything new.
  3. Picture yourself succeeding. One of the key elements for many world-class performers is visualization.

The Day of the Exam

  1. Eat. Don’t skip the meal before your exam because not eating can result in tiredness and poor concentration.
  2. Arrive just a few minutes before your exam to avoid the usual widespread and contagious panic

During the Exam

  1. Use a cheat sheet even if you’re not allowed to bring one into the exam. Make a cheat sheet of the material you are certain will help. Take it to the exam; throw it out before you sit down, then recopy it from memory, somewhere on the exam booklet, as soon as you can.
  2. Read all of the questions (except multiple choice) before beginning, and write notes on the paper for anything important that occurs to you as you read.
  3. If you’re having a problem with one question move on and return to the problem question if you have time left at the end.
  4. Watch the clock.

The Best Way to Study If Your Chemistry Exam Is Tomorrow 

While no one really recommends cramming, sometimes that’s what you have to do. So here are some hints to get you through it:

  1. Pick the most important subjects in your study material.
  2. Look over your lecture notes, or someone else’s if you don’t have any, and see what the lecturer focused on. Concentrate your cramming on these broad areas. You don’t have time to learn specifics.
  3. The key to cramming is memorization, so it only works for “knowledge” questions. Focus on material that can be memorized.
  4. Spend 25% of your time cramming and 75% drilling yourself. Recite and repeat the information.
  5. Relax: being upset at yourself for not studying earlier won’t help and may hurt your performance in the class
  6. Remember how you felt while studying and while writing the exam and plan to study earlier next time!

Hints

  • Be realistic. No one can study for 8 hours a day
  • Make sure you get plenty of food and sleep
  • Try to study in a quiet place
  • Rewrite your notes. It can help you retain information
  • Read your notes out loud

The Day of the Exam

  1. Eat. Don’t skip the meal before your exam because not eating can result in tiredness and poor concentration.
  2. Arrive just a few minutes before your exam to avoid the usual widespread and contagious panic

During the Exam

  1. Use a cheat sheet even if you’re not allowed to bring one into the exam. Make a cheat sheet of the material you are certain will help; take it to the exam; throw it out before you sit down, then recopy it from memory, somewhere on the exam booklet, as soon as you can.
  2. Read all of the questions (except multiple choice) before beginning, and write notes on the paper for anything important that occurs to you as you read.
  3. If you’re having a problem with one question move on and return to the problem question if you have time left at the end.
  4. Watch the clock.

WAEC Chemistry Past Questions 2020 PAPER 2 (ESSAY)

SECTION A

1. Compound A consisting of carbon and hydrogen only. The compound was found to contain 80% carbon by mass.
(a) Calculate the empirical formula of compound A using the data above.
(b) The relative molecular mass of compound A was found to be 30.
Use this information to deduce the molecular formula of compound A.
[H = 1.00 C = 12.00]

2. (a) When calcium oxide and coke are heated in an electric furnace, the products are carbon (ii) oxide and calcium carbide (CaC2), write the equation for this reaction.

(b) The addition of water to calcium carbide leads to the formation of calcium hydroxide and ethyne. Write the equation for the production of ethyne.

3. Calculate the percentage by mass of silicon tetrachloride. [2 marks]
4. Ammonia, NH3, and phosphine, Ph3, are the hydrides of the first two elements in group 5.
(a) Draw a dot and cross diagram for the ammonia molecule. [2 marks]
(b) Sketch and explain the shape of the ammonia molecule. [3 marks]

5. The first ionization energy of chlorine is +1260KJmol-1.
(a) Define the term first ionization energy.
(b) State and explain the general trend in the values of the first ionization energy for the elements across the period, sodium to argon in the periodic table.

6. An aqueous solution has a pH of 4.0.
(a) (i) What is the hydrogen ion concentration of the solution?
(ii) What effect will it have on litmus paper?
(iii) Which of the following salt solutions would have the same effect on litmus? Give a reason for your answer. NH4Cl(aq); NaCl(aq) ; CH3OON(aq).
(b) (i) Differentiate between a fine chemical and a heavy chemical.
(ii) Name two sources of air pollution.
(iii) Suggest one way of reducing air pollution in cities

WAEC Chemistry Past Questions SAMPLE QUESTIONS PAPER 1 (OBJECTIVE TEST)

1. Isotopes of the same element have the same number of

A. Protons, neutrons, and electrons.
B. Protons and neutrons but a different number of electrons.
C. Protons and electrons but different number of neutrons.
D. Neutrons and electrons but a different number of protons.

2. Which type of chemical bond is formed by the transfer of electrons?
A. Covalent
B. Dative
C. Ionic
D. Metallic

3. The concentration of an aqueous solution is 5mg dm-3. Determine is the concentration in parts per million (ppm).
A. 500 ppm
B. 50 ppm
C. 10 ppm
D. 5 ppm

4. Consider the following species: H, H+, H-. What is the number of electrons in each of the species respectively?
A. 1, 0, 2
B. 0, 1, 2
C. 2, 1, 0
D. 1, 2, 0

5. Two electrons can occupy the same orbital if they have different
A. Angular momentum quantum numbers.
B. Magnetic quantum numbers.
C. Principal quantum numbers.
D. Spin quantum numbers.

6. What mass of NaOH is required to make 250 cm3 of 0.10mol/dm-3 solution? [Na = 23, O = 16, H = 1]
A. 1 g
B. 4 g
C. 8 g
D. 16 g

7. Which of the following substances is not a hydrocarbon?
A. Benzene
B. Butane
C. Ethyne
D. Ethanamide

8. A substance which ionizes completely into hydroxonium ions is a
A. Strong acid.
B. Strong base.
C. Weak acid.
D. Weak base.

9. Which of the following solutions is able to resist changes in pH when small amounts of an acid or a base is added?
A. Buffer solution
B. Neutral solution
C. Saturated solution
D. Supersaturated solution

10. Protein is a polymer formed from the linkage of
A. Amino acid molecules.
B. Fatty acid molecules.
C. Glucose units.
D. Monosaccharides.

11. The bond formed between H2OH2O and H+H+ to form the hydroxonium H3O+H3O+ is

A) Dative

B) Covalent

C) Electrovalent

D) Ionic

12. The minimum amount of energy required for effective collisions between reacting particles is known as

A) Activation energy

B) Bond energy

C) Kinetic energy

D) Potential energy

13. An element XX forms the following oxides X2O,XOX2O,XO and XO2.XO2. This phenomenon illustrates the law of ________

A) Conservation of mass

B) Definite proportion

C) Mass action

D) Multiple proportions

14. How many moles of oxygen would contain 1.204×10241.204×1024 molecules?
NB: Avogadro’s constant (NA) =6.02×1023=6.02×1023

A) 1

B) 2

C) 3

D) 4

15. Which of the following statements about solids is correct?

A) Solid particles are less orderly than those of a liquid

B) Solid have lower densities than liquids

C) Solid particles have greater kinetic energies than those of liquids

D) Solid particles cannot be easily compressed

16. Which of the following apparatus can be used to measure a specific volume of a liquid accurately?

A) Beaker

B) Conical flask

C) Measuring cylinder

D) Pipette

17. The general gas equation PVT=KPVT=K is a combination of

A) Boyle’s and Charles’ laws

B) Boyle’s and Graham’s laws

C) Charles’ and Graham’s laws

D) Dalton’s and Graham’s laws

18. The spreading of the scent of a flower in a garden is an example of ______

A) Brownian motion

B) Diffusion

C) Osmosis

D) Tyndal effect

19. Propane and carbon (IV) oxide diffuse at the same rate because [H = 1.00, C = 12.0, O = 16.0]

A) They are both gases

B) Their molecules contain carbon

C) They have the same relative molecular mass

D) Both are denser than air

20. The energy which accompanies the addition of an electron to an isolated gaseous atom is

A) Atomization

B) Electronegativity

C) Electron affinity

D) Ionization

Kindly use your school endpoints.

(1a)
Burette reading (cm)³|1st reading|2na Reading|3rd reading|
Final |15.25|30.53|45.79|
Initial |0.00|15.25|30.53|
Volume of acids used |15.25|15.28|15.26

Average volume of acid used =15.25+15.26/2
=15.255cm³
=15.26cm³
Or =15.27cm³

(1b)
Given; mass con of A =5g/500cm³ = 5g/0.5dn³
CA=10g/dm³
A is HNO3
Therefore molar mass =1+14+(16*3)=15+48=63g/mol¹

Molarity of A = gram con/molar mass
CA=10/63=0.1587mol/dm3

(1bii)
Using CAVA/CBVB =Na/NB
With reacting equation ; HNO³ + NaOH—NaNO3+H2O
nA=1 nB=1
0.1587*15.26/CB*25.00=1/1
25CB=0.1587*15.26
CB=0.1587*15.26/25
CB=0.09687mol/dm³

(1biii)
B is NaOH
Molar mass
23+16+1=40g/mol
Conc of B in g/dm³=molarity * molar mass
= 0.09687*40
=3.8748g/dm³

(1biv)
No of moles present in 250cm³ of NaOH is =molar conc * volume
=0.09687*250/1000
=0.0242moles
Mole ratio of NaOH and NaNO3 is 1;1
No; of mole of NaNO3 which reacted is 0.0242
Mass of NaNO3 formed =molar mass * no; of moles
=85*0.0242
=2.05grams


(1biv)
No of moles present in 250cm³ of NaOH is =molar conc * volume
=0.09687*250/1000
=0.0242moles
Mole ratio of NaOH and NaNO3 is 1;1
No; of mole of NaNO3 which reacted is 0.0242
Mass of NaNO3 formed =molar mass * no; of moles
=85*0.0242

(2a)
TEST: C+burning splint

OBSERVATION: Sample C burst into flame .It burns with non smoky blue flame without soot. Colorless gas that turns wet blue litmus paper faint red and turns like water milky is present.

INFERENCE: C is volatile and flammable. The gas is CO2 from combustion of saturated organic compound.

(2bi)
TEST: C + distilled water + shake

OBSERVATION: Clear or colorless solution is observed

INFERENCE: C is miscible with water

(2bii)
TEST: C + Acidified K2Cr207

OBSERVATION: Orange color of K2Cr207 solution turns pale green and eventually pale blue on cooling

INFERENCE: C is a reducing agent

(2d)
Compound belongs to the class of secondary alkanol
===============================

(3ai)
Zinc nitrate

(3aii)
2 Zn(NO 3 )2 —–>2 ZnO + 4 NO 2 + O 2

(3aiii)
It turns white when cold from it yellow colour when it was hot

(3b)
Pipette / measure 50.0cm3 of the stock solution into a 250
cm3 volumetric flask (containing some distilled water). Shake / swirl and add more distilled water until the mark is reached.

(3c)
Al2(SO4)3 – turns blue litmus red

Waec Chemistry Answers 2022 for 8th June 2022

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