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post-utme2018chemistry
Q1. A quantity of electricity liberates 3.6 g of silver from its salt. What mass of aluminium will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108]
A2.7 g
B1.2 g
C0.9 g
D0.3 g
Correct Answer: D
Moles of Ag deposited = 3.6/108 = 0.0333 mol. Ag⁺ + e⁻ → Ag (n=1), so charge = 0.0333 F. Al³⁺ + 3e⁻ → Al (n=3), so moles of Al = 0.0333/3 = 0.01111 mol. Mass of Al = 0.01111 × 27 = 0.30 g.
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post-utme2018chemistry
Q2. The IUPAC name for the compound (CH₃)₂CH-CH₂-CH₃ shown in the structural diagram is
A1-methyl pentane
B3-methylbutane
C2-methylbutane
D1-dimethyl propane
Correct Answer: C
The structure shows a carbon bearing two CH₃ groups connected to CH₂-CH₃. This is (CH₃)₂CHCH₂CH₃. The longest chain has 4 carbons (butane), with a methyl branch at C2. IUPAC name: 2-methylbutane.
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post-utme2018chemistry
Q3. The type of bonding in [Cu(NH₃)₄]²⁺ is
Acoordinate
Belectrovalent
Cmetallic
Dcovalent
Correct Answer: A
In [Cu(NH₃)₄]²⁺ (tetraamminecopper II complex), the four NH₃ ligands donate lone pairs of electrons to the Cu²⁺ ion to form dative (coordinate) bonds. Both electrons in each bond come from the nitrogen atom of NH₃. This type of bonding — where one atom provides both electrons — is called coordinate (dative covalent) bonding.
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post-utme2018chemistry
Q4. mE + nF → pG + qH. In the equation shown, the equilibrium constant is given by
A[E]ᵐ[F]ⁿ / [G]ᵖ[H]ᵍ
B[E][F] / [G][H]
C[G]ᵖ[H]ᵍ / [E]ᵐ[F]ⁿ
D[G][H] / [E][F]
Correct Answer: C
The equilibrium constant Kc = [products]stoich / [reactants]stoich. For mE + nF ⇌ pG + qH: Kc = [G]ᵖ[H]ᵍ / [E]ᵐ[F]ⁿ. Concentrations of products (raised to their stoichiometric coefficients) are placed in the numerator, and concentrations of reactants in the denominator.
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post-utme2018chemistry
Q5. In the preparation of oxygen by heating KClO₃ in the presence of MnO₂, only moderate heat is needed because the catalyst acts by
Alowering the pressure of the reaction
Bincreasing the surface area of the reaction
Cincreasing the rate of the reaction
Dincreasing the energy barrier of the reaction
Correct Answer: C
MnO₂ acts as a catalyst in the decomposition of KClO₃: 2KClO₃ → 2KCl + 3O₂. A catalyst increases the rate of the reaction by providing an alternative reaction pathway with a lower activation energy. This means only moderate heat is required — the reaction proceeds faster at a lower temperature than without the catalyst.
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post-utme2018chemistry
Q6. When air which contains oxygen, nitrogen, carbon dioxide, water vapour and the rare gases is passed through alkaline pyrogallol and then over quicklime, the only gases left are
Anitrogen and carbon dioxide
Bthe rare gases
Cnitrogen and oxygen
Dnitrogen and the rare gases
Correct Answer: D
Alkaline pyrogallol absorbs O₂ from air. Quicklime (CaO) absorbs CO₂ and water vapour: CaO + CO₂ → CaCO₃; CaO + H₂O → Ca(OH)₂. After these treatments, only nitrogen (unreactive, not absorbed) and the rare gases (noble gases, chemically inert) remain.
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post-utme2018chemistry
Q7. To what volume must 300 cm³ of 0.60 M sodium hydroxide solution be diluted to give a 0.40 M solution?
A450 cm³
B300 cm³
C200 cm³
D150 cm³
Correct Answer: A
Using C₁V₁ = C₂V₂. C₁ = 0.60 M, V₁ = 300 cm³, C₂ = 0.40 M. V₂ = (0.60 × 300)/0.40 = 180/0.40 = 450 cm³. The solution must be diluted to a total volume of 450 cm³.
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post-utme2018chemistry
Q8. A given amount of gas occupies 10.0 dm³ at 4 atm and 273°C. The number of moles of the gas present is? [Molar volume of gas at s.t.p = 22.4 dm³]
A0.89 mol
B1.90 mol
C3.80 mol
D5.70 mol
Correct Answer: A
First convert to STP using combined gas law: V(STP) = P₁V₁T₂/(T₁P₂) = (4 × 10 × 273)/(546 × 1) = 20.0 dm³. Note: T₁ = 273°C + 273 = 546 K, T₂ = 273 K (STP). Moles = 20.0/22.4 = 0.89 mol.
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post-utme2018chemistry
Q9. A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that
Acollisions are perfectly elastic
Bforces of repulsion exist
Cforces of repulsion and attraction are in equilibrium
Dcollisions are inelastic
Correct Answer: A
Gas molecules moving in straight lines between collisions implies there are no intermolecular forces acting on them during flight. The fact that they bounce off each other and the walls without loss of kinetic energy means the collisions are perfectly elastic. This is a key postulate of the kinetic theory of ideal gases.
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post-utme2018chemistry
Q10. The boiling of fat and aqueous caustic soda is referred to as
Ahydrolysis
Besterification
Cacidification
Dsaponification
Correct Answer: D
Saponification is the alkaline hydrolysis of fats (esters of glycerol and fatty acids) with caustic soda (NaOH) to produce soap (sodium salts of fatty acids) and glycerol. The term comes from "sapo" (Latin for soap). Esterification is the reverse reaction (forming esters from acids and alcohols).