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Thursday, 20th November, 2025
Chemistry 2 (Essay) – 2hrs – 08:30 hrs – 10:30 hrs.
Chemistry 1 (Objective) – 1hr – 10:30 hrs – 11:30 hrs.

PLs-NOTE: kindly trace it from your system. The options are being reshuffled. You might see number 1 as any number, so trace and be fast. You might also see option A as option C, B or D. Just use the answers in words and and trace properly. Kindly Trace it 🙏 carefully to avoid errors!!!!

1: (B) hygroscopic

2; (A) Fructose

3; (C) molecule

4; (C) 2, 2, 4-trimethylpentane.

5; (A) working capital.

6; (C) sublimation.

7; (A) CCI⁴

8; (D) 0.040 moldm-³

9; (C) Fe(s) +Cl_²(g) FeCl-²

10; (B) is attacked by moist air.

11: (B) N²(g) + O²(g)—>2NO(g)

12: (A) 19 protons, 19 electrons and 20 neutrons

13: (D) HNO³

14: (A) in which large hydrocarbon molecules are broken into smaller units

15: (A) AgF

16: (B) +6

17: (B) ΔH₁ < ΔH₂

18: (C) neutral

19: (D) CuO

20; (D) 1.00 mol

21: (B) are widely spaced.

22: (A) activation energy

23: (C) less dissociated in solution.

24: (B) almost the entire mass of the atom is in the nucleus.

25: (B) 0.05 mol/dm³

26: (B) occurs in gases.

27: (D) Displacement.

28: (D) paraffin oil.

29: (D) Hex-1-ene.

30: (B) Na, Mg, Al.

31: (B) Alkaline earth metals

32: (C) I-

33: (C) saturated solution

34: (A) Iron

35: (C) Cl,Cl-Cl+

36: (D) Atomic number

37: (C) cracking

38: (A) Na²CO³

39: (C) Si

40: (B) C + e – —-> C-

41: (A) electron

42: (C) solubility

43: (D) tertiary alkanol

44: (C) H²CO³

45: (B) neutral oxides

46: (B) Separation of sand from water

47: (D) rise in boiling point and fall in melting point.

48: (A) hardness

49: (D) melting

50: (A) esterification

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CHEMISTRY NUMBER ONE

(1) (i) Law of conservation of mass – mass is neither created nor destroyed in a chemical reaction.

(ii) Law of definite proportions (constant composition) – a given compound always contains the same elements in the same fixed proportion by mass.

(iii) Law of multiple proportions – when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in small whole-number ratios.

(b) Standard solution
A solution whose concentration is accurately known (prepared by dissolving a known mass of solute and making up to a known volume). Used as a reference in titrations and volumetric analysis.

(c)
Iodine molecules (I₂) are larger and more polarizable than bromine molecules (Br₂), so iodine has stronger London (dispersion) forces. Stronger intermolecular forces mean higher melting/boiling points — iodine is solid at room temperature while bromine (weaker forces) is a liquid.

(d) Dalton’s law of partial pressures
The total pressure of a mixture of non-reacting gases equals the sum of the partial pressures of each gas (each partial pressure is the pressure the gas would exert if it alone occupied the volume at the same temperature).

(e)
(i) Intermolecular attractions (or repulsions) between gas particles.

(ii)Finite (non-negligible) volume of gas particles.

(f)
(i) Reason molten aluminium chloride does not conduct electricity: it does not have free mobile ions — AlCl₃ is largely covalent (often dimeric as Al₂Cl₆), so few free ions to carry charge.
(ii) Two factors responsible:

High polarizing power of the small, highly charged Al³⁺ which induces covalent character.

Formation of covalent dimers/polymeric structures (Al₂Cl₆), reducing the number of free ions.

(g)
(i) Metals: Sodium (Na), Magnesium (Mg) (also Aluminium, Al).
(ii) Non-metals: Phosphorus (P), Sulfur (S) (also Chlorine, Cl).

(h)
(i)Fuels (e.g., methane, propane, butane for heating, cooking and vehicle fuel).

==============================

(2ai)
A transition element is a d-block element that has an atom or ion with an incomplete d-subshell.

(2aii)
(α) Coloured compound formation: Transition metals form coloured compounds due to d-d electron transitions within the partially filled d-orbitals when they absorb certain wavelengths of light.

(β) Complex ion formation: Transition metals can form complex ions by bonding with ligands due to their ability to use empty d orbitals for coordinate covalent bonding.

(γ) Catalytic abilities: Transition metals act as catalysts because they can change oxidation states easily and provide a surface for reactants to adsorb, lowering activation energy.

(2bi)
(α) Potassium and oxygen: K₂O
(β) Sulphur and aluminium: Al₂S₃
(γ) Nitrogen and magnesium: Mg₃N₂

(2bii)
K₂O: Potassium oxide
Al₂S₃: Aluminium sulphide
Mg₃N₂: Magnesium nitride

(2ci)
(α) Atom
An atom is the smallest particle of an element that can exist alone and retains the chemical properties of that element; it consists of a nucleus (protons and neutrons) surrounded by electrons.

(β) Molecule
A molecule is a neutral group of two or more atoms chemically bonded together, representing the smallest particle of a substance that can exist while retaining its chemical identity.

(γ) Ion
An ion is an atom or group of atoms that has acquired a net electrical charge by losing or gaining electrons.

(2cii)
Atom: Cl (chlorine atom)
Molecule: Cl₂ (chlorine molecule)
Ion: Cl⁻ (chloride ion)

=================================

3ai)Hydrochloric acid with zinc metal
Zn + 2HCl -> ZnCl₂ + H₂

(ii) Hydrochloric acid with zinc oxide
ZnO + 2HCl -> ZnCl₂ + H₂O

(iii) Hydrochloric acid with zinc trioxocarbonate(IV) (“zinc trioxocarbonate(IV)” = zinc carbonate, ZnCO3)
ZnCO₃ + 2HCl -> ZnCl₂ + CO₂ + H₂O

(3b)
Moles of sodium (Na):
moles Na = (4.6g) /23g mol⁻¹ = 0.2 mol

Number of atoms in 4.6 g Na:
atoms = 0.2 mol × 6.02 × 10²³ atoms mol⁻¹ = 1.204 × 10²³ atoms

Moles of H₂ required = (1.204 × 10²³)/ (6.02 × 10²³) = 0.2 mol.

molar mass of H₂ = 2g mol⁻¹.
mass of H₂ = 0.2mol × 2g mol⁻¹ = 0.4 g

(3c)
(i) Hydration (addition of water)
(ii) Concentrated H₂SO₄(sulphuric acid)
(iii) Presence of acid catalyst and suitable temperature
(iv) Propene: CH₃-CH=CH₂
Product C₃H₈O (major): CH₃-CH(OH)-CH₃

(v) Chemical equation (hydration, showing catalyst):
CH₃CH=CH₂ + H₂O —> CH₃CH(OH)CH₃ (H₂SO₄ to be written at the top of the arrow)

(vi) 2‑Propanol (propan‑2‑ol)

=========================
(5a)
(i)2NaOH + Cl_2 NaCl + NaClO + H2O
(ii)Cl_2 + H2O HOCl + HCl

(5aii)
(I)Chlorine: Gas
(II) Fluorine: Gas
(III) Astatine: Solid

(5aiii)
The strength of Van der Waal’s forces increases down the group due to the increase in atomic size and polarizability.

(5bi)
(i)Low temperature
(ii)High pressure

(5bii)
The choice of conditions is governed by Le Chatelier’s principle, which states that a system at equilibrium will adjust to counteract any changes in concentration, temperature, or pressure.

(5biii)
(i) For fertilizer production.
(ii)For cleaning agent
(iii)For Industrial applications

(5ci)
(i)High electrical conductivity
(ii)Ductility
(iii)Resistance to corrosion

(5cii)
(i)Oxidizing properties.
(ii)Antimicrobial activity.

(5di)
(i)For Construction.
(ii)It is use as an food and nutrition for humans.
(iii)It is use for manufacturing products, including paper, glass, and ceramics.

(5dii)
(i)Coke
(ii)Coal tar