If you are a candidate seeking Chemistry NECO Questions and Answers  for 2023, you have arrived at the right place as we will break them down for you. We will go further to show you how Chemistry NECO Questions are set and the best way to answer for full marks.

Chemistry NECO Questions and Answers

The National Examinations Council is an examination body in Nigeria that conducts the Senior Secondary Certificate Examination and the General Certificate in Education in June/July and December/January, respectively.

NECO Chemistry Objectives and Essay Answers 2023

1-10EBAAAAAACC

11-20BCBCACADCA

21-30AACBDDAACD

31-40CCACCACCDE

41-50EDCCDDBDAC

51-60CBACCDCBCD

 

(1ai)

(i) KAl(SO₄)₂. 12H₂O

(ii) Na₂SO₄

(1aii)

Number of moles of sodium reacted = reacting mass/molar mass

= 3.6/23

= 0.1565moles

Number of moles of oxygen reacted = (1/4) x Number of sodium

= 1/4 x (3.6/23)

= 0.03913

Reacting mass of oxygen = Number of moles x molar mass

= 0.03913 x (16×2)

= 1.252grams

 

(1bi)

Air in gaseous form is first passed through caustic soda to remove CO₂. It is compressed and cooled until it becomes a liquid at -200°C. It is then led to a fractionating column. On distillation, Nitrogen which has a low boiling point of -196°C evolved first leaving behind Oxygen in liquid form. Further heating converts the liquid to a gas at -183°C.

(1bii)

(i) It is used for combustion

(ii) It is used for artificial respiration

(1biii)

This is because room temperature is warmer

(1biv)

(i) Methyl orange

(ii) Phenolphthalein

(1ci)

An ion is an atom or molecule which has a net electric charge due to the loss or gain of one or more electrons.

(1cii)

HCl gas doesn’t contain ions

(1cii)

(i) Noble gases: Neon, Helium

(ii) Halogens: Iodine, Fluorine

(iii) Alkaline earth metals: Calcium, Magnesium

(1civ)

Halogens attain stable octet configuration by accepting an electron from donors’ Group I elements.

(1di)

Sol is a colloid where solid particles are dispersed in a liquid medium.

(1dii)

Jelly

(1diii)

(i) Acid-base titrations are used to determine the percentage purity of a substance

(ii) Acid-base titrations are important to determine the number of water molecules in a hydrate.

 

(2ai)

A molar solution of a compound contains one mole or the molar mass of the compound in one dm³ of the solution.

(2aii)

(i) Identification of gases

(ii) Identification of acidic and metallic radicals

(2aiii)

(i) Purification of bauxite

(ii) Electrolysis of alumina

(2bii)

This is because of the presence of copper which is a transition metal

(2bii)

(i) Methanamide is a liquid while the rest amides are crystalline solids

(ii) Melting points and boiling points of aides are much higher than expected.

(2ci)

(i) Heavy chemicals are produced in very large quantities in industries While fine chemicals are produced in small quantities for specific purposes

(ii) Heavy chemicals are in a crude state while fine chemicals are purified.

 

(2cii)

(i) Million’s reagent

(ii) Feeling’s solution

(2ciii)

Graham’s law of diffusion states that at a constant temperature and pressure, the rate of diffusion of a gas is inversely proportional to the square root of its density.

(2civ)

RO₂/RCH₄ = √(MCH₄/MO₂)

5/(200/t) = √[(12+4)/(16×2)]

5t/200 = √16/32

t/40 = 1/√2

t = 40/√2

t = (40/√2) × (√2/√2)

t = 20√2 seconds

Time taken = 28.28 seconds

Read Also!!

5ai)

(i)Chlorofluorocarbons

(ii) Hydrofluorocarbon

(5aii)

I – C₂H₂OH + H₂SO₄ —>C₂H₅HSO₄ + H₂O

II – C₂H₅HSO₄ —> C₂H₄ +H₂SO₄

(5aiii)

(i) They incompletely filled d-orbitals

(ii) They exhibit variable oxidation state

(5bi)

(i) It is used in making aeroplane parts due to its tensile strength

(ii) It is used in making window frames because it cannot be easily oxidised

(5bii)

A white precipitate is formed with the evolution of brown gas

(5biii)

(i) Hydrogen bond

(ii) Covalent bond

(5ci)

(i) Oxidation

(ii) Electrolysis

(5cii)

(i)Temperature

(ii)Concentration

(5ciii)

H₂SO₄ + 2NaOH —> Na₂SO₄ +2H₂O

CaVa/CbVb = Na/NB

Va = CbVbna/Can

Va = 0.1×25×1/0.5×2

Va = 2.5cm³

 

(6ai)

The rate of a chemical reaction is defined as the number of moles of reactant converted or product formed per unit time.

(6aii)

Mass of CaCO3 = 3g

Molar mass of CaCO3= 100g/mol

No. of moles = 3/100 = 0.03

Time = 2×60 = 120s

Rate of reaction = No. of moles/Time = 0.03/120 = 2.5 × 10-⁴

(6aiii)

(i) They are more resistant to corrosion

(ii) They are more durable

(iii) They have a lower melting point

(6aiv)

2Pb(NO₃)₂ —> 2PbO + 4NO₂ +O₂

(6bi)

I =Hard water=

(i)It has better taste than soft water

(ii) It can be supplied in lead pipes as it does not dissolve lead

II =Soft water=

(i) It does not deposit scale in boilers and fur in kettles

(ii) It does not waste soap

(6bii)

I – CO

II – SO₂

(6biii)

I – Hardness

II – Lustre appearance

III – Conductivity

IV – Ability to absorb

(6c)

4.3/2.12 = 142+18x/142

2.12(142+18x)/2.12 = 4.3*142/2.12

142+18x = 288

18x = 288-142

x = 146/18

x = 8

Chemistry NECO Questions for 2023

The following NECO Chemistry questions are questions to expect in the 2022 NECO examination.

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

A) Activation of energy

B) Bond energy

C) Kinetic energy

D) Potential energy

 

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

A) Dative

B) Covalent

C) Electrovalent

D) Ionic

 

3. 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

 

4. 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

 

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

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

B) Solids have lower densities than liquids

C) Solid particles have greater kinetic energies than those liquids

D) Solid particles cannot be easily compressed

 

6. 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

 

7. 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

 

8. The spreading of the scent of a flower in a garden is an example of a?

A) Brownian motion

B) Diffusion

C) Osmosis

D) Tyndal effect

 

9. 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

 

1O. The energy which accompanies the addition of an electron to an isolated gaseous atom is

A) Atomization

B) Electronegativity

C) Electron affinity

D) Ionization

 

11. A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by

A. boiling the water

B. adding excess calcium hydroxide

C. adding a calculated amount of calcium hydroxide

D. adding sodium carbonate

E. adding magnesium hydroxide

 

12. During the electrolysis of copper II sulphate between platinum electrodes, if litmus solution is added to the anode compartment,

A. the litmus turns blue but no gas is evolved

B. the litmus turns blue and oxygen is evolved

C. the litmus turns blue and hydrogen is evolved

D. the litmus turns red and oxygen is evolved

E. the litmus turns red and then becomes colourless

 

13. The reaction between an organic acid and an alcohol in the presence of an acid catalyst is known as;

A. saponification

B. dehydration

C. esterification

D. hydrolysis

E. hydration

 

14. The IUPAC names of the compounds CH3COOH and CH2=CH2 are respectively;

A. acetic acid and ethane

B. ethanoic acid and ethene

C. methanoic acid and ethylene

D. ethanol and ethene

E. acetic acid and ethylene

 

15. If 30cm3 of oxygen diffuses through a porous pot in 7 seconds, how long will it take 60cm3 of chlorine to diffuse through the same pot, if the vapour densities of oxygen and chlorine are 16 and 36 respectively?

A. 9.3 sec

B. 14 sec

C. 21 sec

D. 28 sec

E. 30.3 sec

 

16. When heat is absorbed during a chemical reaction, the reaction is said to be

A. thermodynamic

B. exothermic

C. isothermal

D. endothermic

E. thermostatic

 

17. When large hydrocarbon molecules are heated at high temperatures in the presence of a catalyst to give smaller molecules, the process is known as

A. disintegration

B. polymerization

C. cracking

D. degradation

E. distillation

 

18. The pH of four solutions W, X, Y, and Z are 4, 6, 8, and 10 respectively, therefore

A.none of these solutions is acidic

B. the pH of Y is made more acidic by the addition of distilled water

C. Z is the most acidic solution

D. W is the most acidic solution

E. X is neutral

 

19. When each of the nitrates of Potassium, Magnesium and iron is heated,

A. all the nitrates decompose to their oxides

B. the nitrate of magnesium gives the nitrite and oxygen

C. the nitrates of iron magnesium and iron give the oxides

D. the nitrate of iron gives the nitrite and oxygen

E. the nitrate of the magnesium is not decomposed

Read Also!

2O. Which of the following metals cannot replace hydrogen from water or steam?

A. Sodium

B. Magnesium

C. Iron

D. Calcium

E. Copper

 

21. A small quantity of solid ammonium chloride (NH4Cl) was heated gently in a test tube, and the solid gradually disappears to produce two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone

A. distillation

B. sublimation

C. precipitation

D. evaporation

E. decomposition

 

22. Elements P, Q, R, and S have 6, 11, 15, and 17 electrons respectively, therefore,

A. P will form an electrovalent bond with R

B. Q will form a covalent bond with S

C. R will form an electrovalent bond with S

D. Q will form an electrovalent bond with S

E. Q will form a covalent bond with R

 

23. An element X forms the following compounds with chlorine; XCl4, XCl3, XCl2. This illustrates the

A. law of multiple proportions

B. law of chemical proportions

C. law of simple proportions

D. law of conservation of mass

E. law of definite proportions

 

24. The oxidation state of chlorine in potassium chlorate is

A. +1

B. +2

C. +3

D. +5

E. +7

 

25.10 When air which contains the gases Oxygen, nitrogen, carbon dioxide, water vapour and rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A. nitrogen and carbon dioxide

B. the rare gases

C. nitrogen and oxygen

D. nitrogen and the rare gases

E. nitrogen, carbon dioxide and the rare

 

26. Which of the following statements is NOT correct?

A.The average kinetic energy of a gas is directly proportional to its temperature

B. At constant temperature, the volume of a gas increases as the pressure increases

C. The pressure of a gas is inversely proportional to its volume

D. The temperature of a gas is directly proportional to its volume

E. The collisions of molecules with each other are inelastic

 

27. Zinc Oxide is a

A. Basic Oxide

B. Acidic Oxide

C. Amphoteric Oxide

D. Neutral Oxide

E. Reactive Oxide

 

28. When sodium chloride and metallic sodium are each dissolved in water

A. both processes are exothermic

B. both processes are endothermic

C. the dissolution of metallic sodium is endothermic

D. the dissolution of metallic sodium is exothermic

E. the dissolution of sodium chloride is explosive

 

29. The periodic classification of elements is an arrangement of the elements in the order of their

A. Atomic Weights

B. Isotopic Weights

C. Molecular Weights

D. Atomic Numbers

E. Atomic Masses

 

3O. In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?

A.5cm3

  1. 0cm3

C.20cm3

D.25cm3

E.50cm3

DISCLAIMER! These are not real Chemistry NECO Questions and Answers but likely repeated questions over the years to help candidates understand the nature of their examinations. Ensure to take note of every question provided on this page.

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