Real 2023 NECO Chemistry Questions & Answers (OBJ-Essay) Released

Real 2023 NECO Chemistry Questions and Answers. I will be teaching you past Chemistry objectives and theory repeated questions for free of charge in this post. You will also know how Real 2023 NECO Chemistry questions are structured and how to answer them.NECO Accounting Questions and Answers 2022/2023 (Essay and Objectives)

Real 2023 NECO Chemistry Answers

CHEMISTRY-Obj!
1-10 DEADADECAD
11-20 BAEDDBDBAE
21-30 CCDCABDDCD
31-40 EBEECEBCEE
41-50 BCCECDDADD
51-60 DABBDEAECA

Completed!!

ANSWERS NUMBER 1

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QUESTION CHEMISTRY (1)

(1ai)
(i) Manufacturing sulfuric acid
(ii) Vulcanization of rubber
(iii) Formulation of Pesticides and fungicides

(1aii)
(i) It is a colorless gas that has a distinct smell of rotten eggs
(ii) Hydrogen sulphide is soluble in water to some extent

(1aiii)
Soaps are made from natural products while detergents are made from synthetic products.

(1aiv)
Detergents is for household cleaning and laundry purposes

(1bi)
Number of neutrons = Mass number (A) – Atomic number (Z)
I. ²³₁₁X
A = 23 (mass number)
Z = 11 (atomic number)

Number of neutrons = 23 – 11 = 12
II. ³⁹₁₉Y
A = 39 (mass number)
Z = 19 (atomic number)
Number of neutrons = 39 – 19 = 20

(1bii)
Molar mass:
Na = 22.99 g/mol
O₂ = 2 * 16.00 g/mol = 32.00 g/mol
Now, let’s calculate the mass of oxygen needed:

First, calculate the number of moles of sodium (Na) in 9.2g:
Number of moles = Mass / Molar mass
Number of moles of Na = 9.2g / 22.99 g/mol ≈ 0.4002 mol
Since the mole ratio of Na to O₂ is 4:1, the number of moles of O₂ needed is:
Number of moles of O₂ = 0.4002 mol / 4 ≈ 0.1001 mol
Now, calculate the mass of oxygen needed:
Mass of O₂ = Number of moles of O₂ * Molar mass of O₂
Mass of O₂ = 0.1001 mol * 32.00 g/mol ≈ 3.204 g
Therefore, approximately 3.204 grams of oxygen are needed to burn 9.2 grams of sodium.

(1biii)
CaCO₃(s) + 2 HCl(aq) —> CaCl₂(aq) + CO₂(g) + H₂O(l)
From the balanced equation, 1 mole of calcium carbonate (CaCO₃) reacts with 2 moles of HCl to produce 1 mole of calcium chloride (CaCl₂).
Molar masses:
CaCO₃ = Ca(40.08) + C(12.01) + 3O(16.00) = 100.09 g/mol
CaCl₂ = Ca(40.08) + 2Cl(35.45) = 110.98 g/mol
Now, let’s calculate the number of moles of CaCO₃ in 50g:
Number of moles of CaCO₃ = Mass / Molar mass
Number of moles of CaCO₃ = 50g / 100.09 g/mol ≈ 0.4998 mol
Since the mole ratio of CaCO₃

ANSWERS NUMBER 3

ANSWERS NUMBER 4

Chemistry answers no 4.
(4ai)
A super saturated solution is a solution that contains more than the maximum amount of solute that is capable of being dissolved at a given temperature.

(4aii)
15/345 = Solubility *25/1000

Solubility =1000*15/25*345=15000/8625

Solubility = 1.79mol/dm³

(4aiii)
(i) H₃0⁺
(ii) NH₄⁺
(iii) [CN]⁻₆

(4bi)
(i) It has no chemical formula
(ii) It can be separated physically
(iii) Freezing air slowly yields different liquids at different temperatures

(4bii)
(i) Noble gases
(ii) Carbon (iv) oxide

(4biii)
H₂SO₄ —-> 2H+ + SO₄²⁻

1 mole of H₂SO₄ = 2 mole of H⁺

0.1 mole of H₂SO₄ = 0.2 mole of H⁺
Mole = no. of H⁺/Avogadro’s constant

No. of H⁺ = Mole * Avogadro’s constant
= 0.2 * 6.0*10²³
= 1.2*10²³ ions

(4biv)
(i) Dative bonding
(ii) Hydrogen bonding

(4bv)
(i) BRASS:
Constituent: Copper and zinc.
Use: Brass is used in the production of musical instruments decorative items and plumbing fixtures.

(ii) BRONZE:
Constituent: Copper and tin.
Use: Bronze is used in the production of statues coins and various machinery.

ANSWERS NUMBER 5

(5ai)
A base is a substance which when disolve produce hydroxyl ion (OH⁻) as the only negative ion

(5aii)
(i) K₂O
(ii) MgO

(5aiii)
(i) it is used in printing inks and dyes
(ii) it is used in making photographic chemicals

(5aiv)
Aliphatic does not have good odour while an aromatic hydrocarbon has

(5av)
M.m of XCl₃=10-8+(35-5*3)
=10.8+106.5
=117.3
Vapour density =117.3/2=58.65

(5bi)
(i) Temperature
(ii) concentration
(iii) surface area

(5bii)
The law states that energy can neither be created nor destroyed in and isolated system.

(5biii)
(i) burning of wood
(ii) neutralization reaction

(5c)

ANSWERS NUMBER 6