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Instruction
JAMB Chemistry 1991
JAMB (UTME)
Chemistry
1991
Q8251.A metal is extracted from its ore by the electrolysis of its molten chloride and it displaces lead from lead (II) trioxonitrate (V) solution. The metal is
Acopper
Baluminium
Czinc
Dsodium
Correct Answer: C
Zinc is extracted by electrolysis of its molten chloride (or sulphate). Zinc is more reactive than lead and can displace it from solution. Sodium and aluminium are more reactive than zinc and would react with water.
JAMB (UTME)
Chemistry
1991
Q8252.Mortar is NOT used for under-water construction because
AIt hardens by loss of water
BIts hardening does not depend upon evaporation
CIt requires concrete to harden
DIt will be washed away by the flow of water.
Correct Answer: A
Mortar (a mixture of cement, sand, and water) hardens by chemical reaction (hydration), not by evaporation. It can harden under water.
JAMB (UTME)
Chemistry
1991
Q8253.Which of the following is NOT involved in the extraction of metals from their ores?
Areduction with carbon
Breduction with other metals
Creduction by electrolysis
Doxidation with oxidizing agent
Correct Answer: D
Extraction of metals involves reduction of the metal ion to the metal. Oxidation with an oxidizing agent would not help extract the metal.
JAMB (UTME)
Chemistry
1991
Q8254.Which of the following compounds is an isomer of the compound?
ACH₃CH₂CH₂CH₂CH₃
BCH₃CH(CH₃)CH₂CH₃
CCH₃CH₂CH(CH₃)CH₃
DCH₃CH(CH₃)CH₂CH₂CH₃
Correct Answer: B
The question is incomplete without the original compound. Isomers have the same molecular formula but different structural formulas.
JAMB (UTME)
Chemistry
1991
Q8255.When excess chlorine is mixed with ethene at room temperature, the product is
A1,2-dichloroethane
B1,2-dichloroethene
C1,1-dichloroethane
D1,1-dichloroethene
Correct Answer: A
Ethene reacts with excess chlorine by addition to form 1,2-dichloroethane.
JAMB (UTME)
Chemistry
1991
Q8256.Vulcanization of rubber is a process by which
AIsoprene units are joined to produce rubber
BRubber latex is coagulated
CSulphur is chemically combined in the rubber
DWater is removed from the rubber.
Correct Answer: C
Vulcanization involves heating rubber with sulphur to form cross-links between the polymer chains, making the rubber harder and stronger.
JAMB (UTME)
Chemistry
1991
Q8257.The reaction between ethanoic acid and sodium hydroxide is an example of
Aesterification
Bneutralization
Chydrolysis
Dhydrolysis
Correct Answer: B
The reaction between an acid and a base to form salt and water is neutralization.
JAMB (UTME)
Chemistry
1991
Q8258.The bond which joins two ethanoic acid molecules in the liquid state is
Aa covalent bond
Ban ionic bond
Ca dative covalent bond
Da hydrogen bond
Correct Answer: D
Ethanoic acid molecules form hydrogen bonds with each other in the liquid state due to the presence of the -COOH group.
JAMB (UTME)
Chemistry
1991
Q8259.The alkaline hydrolysis of fats and oils produces soap and
Apropane 1, 1, 3-triol
Bpropane - 1, 3, 3-triol
Cpropane-1,2,2-triol
Dpropane-1,2,3-triol
Correct Answer: D
Alkaline hydrolysis of fats and oils (saponification) produces soap and glycerol (propane-1,2,3-triol).
JAMB (UTME)
Chemistry
1991
Q8260.Which of the following is NOT a monomer?
AC₆H₅CH=CH₂
BCH₂=CH₂
CCH₂=CHCl
DC₆H₆
Correct Answer: D
Benzene (C₆H₆) is not a monomer. The others (styrene, ethene, vinyl chloride) are monomers.
JAMB (UTME)
Chemistry
1991
Q8261.What is the IUPAC name for the compound CH₂=C(CH₃)CH₂Cl?
A1-chloro-2-methylprop-2-ene
B1-chloro-2-methylprop-1-ene
C3-chloro-2-methylprop-1-ene
D3-chloro-2-methylprop-1-ene
Correct Answer: A
The longest chain containing the double bond has 3 carbons (propene). The double bond is at position 1, methyl at position 2, and chloro at position 1. The correct name is 1-chloro-2-methylprop-1-ene.
JAMB (UTME)
Chemistry
1991
Q8262.The gas responsible for most of the fatal explosion in coal mines is
Abutane
Bethene
Cethane
Dmethane
Correct Answer: D
Methane (CH₄), also known as firedamp, is the gas responsible for most fatal explosions in coal mines.
JAMB (UTME)
Chemistry
1991
Q8263.Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature?
AX and Z
BY
CX
DZ
Correct Answer: D
Aromatic hydrocarbons (like benzene) burn with a sooty flame and do not decolorize bromine water. Z burns with a non-sooty flame and does not decolorize bromine water, so it is aromatic.
Instruction
JAMB Chemistry 1992
JAMB (UTME)
Chemistry
1992
Q8264.Which of the following is a physical change?
AThe bubbling of chlorine into water
BThe bubbling of chlorine into a jar containing hydrogen
CThe dissolution of sodium chloride in water
DThe passing of steam over heated iron
Correct Answer: C
Dissolution of sodium chloride in water is a physical change because it can be reversed by evaporation, and no new substance is formed. The other options involve chemical reactions.
JAMB (UTME)
Chemistry
1992
Q8265.Changes in the physical states of a chemical substance T are shown in the scheme below.
Asublimation, condensation and freezing
Bsublimation, vaporization and solidification
Cfreezing, condensation and sublimation
Devaporation, liquefaction and sublimation
Correct Answer: B
X is the direct change from solid to gas (sublimation). Y is the change from gas to liquid (condensation). Z is the change from liquid to solid (solidification/freezing).
JAMB (UTME)
Chemistry
1992
Q8266.In the reaction: SnO₂ + 2C → Sn + 2CO, the mass of coke containing 80% carbon required to reduce 0.032 kg of pure tin oxide is
A0.40 kg
B0.20 kg
C0.06 kg
D0.40 g
Correct Answer: C
Molar mass of SnO₂ = 119 + 32 = 151 g/mol. Moles of SnO₂ = 32/151 = 0.212 mol. Moles of C required = 2 × 0.212 = 0.424 mol. Mass of C = 0.424 × 12 = 5.09 g. Mass of coke (80% C) = 5.09/0.8 = 6.36 g ≈ 0.06 kg. (The provided answer C is a typo).
JAMB (UTME)
Chemistry
1992
Q8267.The Avogadro's number of 24 g of magnesium is the same as that of
A1 g of hydrogen molecules
B16 g of oxygen molecules
C32 g of oxygen molecules
D35.5 g of chlorine molecules
Correct Answer: C
24 g of Mg = 1 mole. 32 g of O₂ = 1 mole. The number of molecules in 1 mole is Avogadro's number. 1 g of H₂ = 0.5 mole. 16 g of O₂ = 0.5 mole. 35.5 g of Cl₂ = 0.5 mole.
JAMB (UTME)
Chemistry
1992
Q8268.If a gas occupies a container of volume 146 cm³ at 18°C and 0.971 atm, its volume in cm³ at s.t.p is
A133
B146
C266
D292
Correct Answer: A
Using combined gas law: (P₁V₁)/T₁ = (P₂V₂)/T₂. P₁ = 0.971 atm, V₁ = 146 cm³, T₁ = 291 K. P₂ = 1 atm, T₂ = 273 K. V₂ = (0.971 × 146 × 273)/(1 × 291) = 133 cm³.
JAMB (UTME)
Chemistry
1992
Q8269.The volume occupied by 1.58 g of a gas at s.t.p is 500 cm³. What is the relative molecular mass of the gas?
Q8270.Equal volumes of CO, SO₂, NO₂ and H₂S were released into a room at the same point and time. Which of the following gives the order of diffusion of the gases to the farthest corner of the room?
ACO₂, SO₂, NO₂, H₂S
BSO₂, NO₂, H₂S, CO
CCO, H₂S, SO₂, NO₂
DCO, H₂S, NO₂, SO₂
Correct Answer: D
Rate of diffusion is inversely proportional to the square root of molar mass. Molar masses: CO = 28, H₂S = 34, NO₂ = 46, SO₂ = 64. Order of increasing molar mass (fastest to slowest) is CO > H₂S > NO₂ > SO₂.
JAMB (UTME)
Chemistry
1992
Q8271.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
The kinetic theory assumes that gas molecules move in straight lines between collisions and that collisions are perfectly elastic (no loss of kinetic energy).
JAMB (UTME)
Chemistry
1992
Q8272.The table above shows the properties of four atoms P, Q, R and S. Which of the four atoms can be described by the following properties: relative atomic mass is greater than 30 but less than 40; it has an odd atomic number and forms a unipositive ion in solution?
AP
BQ
CR
DS
Correct Answer: C
The atom with mass number >30 but <40, odd atomic number, and forming a unipositive ion is R (atomic number 19, potassium, mass number 39).
JAMB (UTME)
Chemistry
1992
Q8273.Which of the following terms indicates the number of bonds that can be formed by an atom?
AOxidation number
BValence
CAtomic number
DElectronegativity
Correct Answer: B
Valence (valency) is the combining power of an element — the number of bonds it can form.
JAMB (UTME)
Chemistry
1992
Q8274.X(g) → X⁺(g) + e⁻
Aionization energy
Bsublimation energy
Clattice energy
Delectron affinity
Correct Answer: A
The energy required to remove an electron from a gaseous atom is ionization energy.
JAMB (UTME)
Chemistry
1992
Q8275.Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5. The relative abundance of the isotope of mass number 37 is
A20
B25
C50
D75
Correct Answer: B
Let abundance of Cl-37 be x, then Cl-35 is (100-x). 35(100-x)/100 + 37x/100 = 35.5. 3500 - 35x + 37x = 3550. 2x = 50. x = 25%.
JAMB (UTME)
Chemistry
1992
Q8276.10.0 dm³ of air containing H₂S as an impurity was passed through a solution of Pb(NO₃)₂ until all the H₂S had reacted. The precipitate of PbS was found to weigh 5.02 g. According to the equation: Pb(NO₃)₂ + H₂S → PbS + 2HNO₃, the percentage by volume of hydrogen sulphide in the air is
A50.2
B47.0
C4.70
D0.47
Correct Answer: C
Molar mass of PbS = 207 + 32 = 239 g/mol. Moles of PbS = 5.02/239 = 0.021 mol. Moles of H₂S = 0.021 mol. Volume of H₂S at s.t.p = 0.021 × 22.4 = 0.47 dm³. Percentage by volume = (0.47/10) × 100 = 4.7%.
JAMB (UTME)
Chemistry
1992
Q8277.A blue solid, T, which weighed 5.0 g was placed on a table. After 8 hours, the resulting pink solid was found to weigh 5.5 g. It can be inferred that substance T
Ais deliquescent
Bis hygroscopic
Chas some molecules of water of crystallization
Dis efflorescent
Correct Answer: C
The blue solid is anhydrous cobalt(II) chloride, which absorbs moisture from the air to become the pink hydrated form. This indicates it has water of crystallization.
JAMB (UTME)
Chemistry
1992
Q8278.The effluent of an industrial plant used in the electrolysis of concentrated brine, with a flowing mercury cathode may contain impurities like
Aoxygen
Bhydrogen
Cmercury (II) chloride
Dhydrogen chloride
Correct Answer: C
The mercury cell process for brine electrolysis can release traces of mercury compounds as impurities.
JAMB (UTME)
Chemistry
1992
Q8279.The solubility in moles per dm³ of 20g of CuSO₄ dissolved in 100g of water at 18°C is
A0.13
B0.25
C1.25
D2.00
Correct Answer: C
Molar mass of CuSO₄ = 63.5 + 32 + 64 = 159.5 g/mol. Moles = 20/159.5 = 0.125 mol. Volume of water = 100 g ≈ 100 cm³ = 0.1 dm³. Solubility = 0.125/0.1 = 1.25 mol dm⁻³.
JAMB (UTME)
Chemistry
1992
Q8280.Smoke consists of
Asolid particles dispersed in liquid
Bsolid or liquid particles dispersed in gas
Cgas or liquid particles dispersed in liquid
Dliquid particles dispersed in liquid
Correct Answer: B
Smoke is an aerosol consisting of solid or liquid particles dispersed in a gas (usually air).
JAMB (UTME)
Chemistry
1992
Q8281.Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9g of sodium oxalate in 50g of water at room temperature, calculate the minimum volume of 0.1 M calcium oxalate required to produce maximum calcium oxalate using the above equation.
A1.40 × 10² dm³
B1.40 × 10² cm³
C1.40 × 10⁻² dm³
D1.40 × 10⁻² cm³
Correct Answer: B
Molar mass of Na₂C₂O₄ = 2(23) + 2(12) + 4(16) = 134 g/mol. Moles = 1.9/134 = 0.0142 mol. Volume of 0.1 M CaCl₂ = 0.0142/0.1 = 0.142 dm³ = 142 cm³ ≈ 1.40 × 10² cm³.
JAMB (UTME)
Chemistry
1992
Q8282.2.0 g of monobasic acid was made up to 250 cm³ with distilled water. 25.00 cm³ of this solution required 20 cm³ of 0.1 M NaOH solution for complete neutralization. The molar mass of the acid is
A200 g
B160 g
C100 g
D50 g
Correct Answer: C
Moles of NaOH = 0.1 × 20/1000 = 0.002 mol. Moles of acid in 25 cm³ = 0.002 mol. Moles in 250 cm³ = 0.02 mol. Molar mass = 2.0/0.02 = 100 g/mol.
JAMB (UTME)
Chemistry
1992
Q8283.What is the concentration of H⁺ ions in moles per dm³ of a solution of pH 4.398?
Q8284.What volume of 11.0 M hydrochloric acid must be diluted to obtain 1 dm³ of 0.05 M acid?
A0.05 dm³
B0.10 dm³
C0.55 dm³
D11.0 dm³
Correct Answer: A
M₁V₁ = M₂V₂. 11.0 × V₁ = 0.05 × 1. V₁ = 0.05/11.0 = 0.0045 dm³ = 4.5 cm³. (The provided options do not have the correct answer).
JAMB (UTME)
Chemistry
1992
Q8285.If 10.8 g of silver is deposited in a silver coulometer connected in series with a copper coulometer, the volume of oxygen liberated is
A0.56 dm³
B5.50 dm³
C11.20 dm³
D22.40 dm³
Correct Answer: A
Moles of Ag = 10.8/108 = 0.1 mol. 1 mole of electrons deposits 1 mole of Ag. So 0.1 F passed. Oxygen liberation: 4OH⁻ → O₂ + 2H₂O + 4e⁻. 4F liberates 1 mole of O₂. 0.1F liberates 0.025 mol O₂. Volume = 0.025 × 22.4 = 0.56 dm³.
JAMB (UTME)
Chemistry
1992
Q8286.0.1 faraday of electricity deposited 2.95 g of nickel during electrolysis in an aqueous solution. Calculate the number of moles of nickel that will be deposited by 0.4 faraday.
A0.20
B0.30
C0.34
D5.87
Correct Answer: A
0.1 F deposits 2.95 g Ni = 2.95/58.7 = 0.05 mol. 0.4 F will deposit 0.05 × 4 = 0.20 mol.
JAMB (UTME)
Chemistry
1992
Q8287.Cr₂O₇²⁻ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ + 6Fe³⁺ + 7H₂O. In the above reaction, chromium changes from
A+6 to +3
B+7 to +3
C+6 to +2
D+7 to +2
Correct Answer: A
In Cr₂O₇²⁻, Cr is +6. In Cr³⁺, it is +3.
JAMB (UTME)
Chemistry
1992
Q8288.In the reaction 10I⁻ + 5I₂ + 6H⁺ → 3I₂ + 3H₂O, the oxidizing agent is
AH⁺
BI⁻
CIO₃⁻
DI₂
Correct Answer: C
The reaction is IO₃⁻ + 5I⁻ + 6H⁺ → 3I₂ + 3H₂O. IO₃⁻ is reduced to I₂, so it is the oxidizing agent.
JAMB (UTME)
Chemistry
1992
Q8289.Fe₂O₃(s) + 2Al(s) → Al₂O₃(s) + 2Fe(s). Given that the heats of formation of Fe₂O₃ and Al₂O₃ are -1670 kJ mol⁻¹ and -822 kJ mol⁻¹ respectively, the enthalpy change in kJ for the reaction is
A+2492
B+848
C-848
D-2492
Correct Answer: C
ΔH = ΣΔHf(products) - ΣΔHf(reactants) = [(-822)] - [(-1670)] = -822 + 1670 = +848 kJ. (Note: The provided answer C is a typo; the correct answer is +848 kJ).
JAMB (UTME)
Chemistry
1992
Q8290.Iron galvanized with zinc is cathodically protected from corrosion. This is because
Azinc has a more positive oxidation potential than iron
Bzinc has a less positive oxidation potential than iron
Cboth have the same oxidation potential
Dzinc is harder than iron
Correct Answer: B
Zinc is more electropositive (more reactive) than iron. It acts as a sacrificial anode, corroding instead of the iron.
JAMB (UTME)
Chemistry
1992
Q8291.Which of the following samples will react faster with dilute trioxonitrate (V) acid at 25°C?
A5g of lump CaCO₃ at 25°C
B5g of powdered CaCO₃ at 25°C
C5g of lump CaCO₃ at 35°C
D5g of powdered CaCO₃ at 50°C
Correct Answer: D
The rate of reaction increases with increasing temperature and increasing surface area (powdered form). Highest temperature and smallest particle size give the fastest reaction.
JAMB (UTME)
Chemistry
1992
Q8292.In the reaction, 2HI(g) ⇌ H₂(g) + I₂(g); ΔH = 10 kJ, the concentration of iodine in the equilibrium mixture can be increased by
Araising the pressure
Braising the temperature
Cadding a catalyst
Dlowering the pressure
Correct Answer: B
The forward reaction is endothermic (ΔH positive). Increasing temperature favours the forward reaction, increasing the concentration of iodine.
JAMB (UTME)
Chemistry
1992
Q8293.Which of the following gases can be collected by upward displacement of air?
ANO
BH₂
CNH₃
DCl₂
Correct Answer: D
Upward displacement of air is used for gases that are heavier than air (denser than air). Chlorine (Cl₂) is denser than air.
JAMB (UTME)
Chemistry
1992
Q8294.The brown fumes given off when trioxonitrate (V) acid is heated consist of
ANO₂ and O₂
BH₂O and NO₂
CNO₂, O₂ and H₂O
DNO₂ and H₂O
Correct Answer: A
When trioxonitrate(V) acid (HNO₃) is heated, it decomposes to give NO₂ (brown gas), O₂, and H₂O. The brown fumes are mainly NO₂.
JAMB (UTME)
Chemistry
1992
Q8295.Which of the following tests will completely identify any one of sulphur (IV) oxide, hydrogen, carbon (IV) oxide and nitrogen (II) oxide?
Apass each gas into water and test with blue litmus paper
Bpass each gas into limewater
Cexpose each gas to atmospheric air
Dpass each gas into concentrated tetraoxosulphate (VI) acid
Correct Answer: C
Exposing each gas to air: NO (colourless) turns brown (NO₂). H₂S smells rotten. SO₂ has a pungent smell. CO₂ is odourless.
JAMB (UTME)
Chemistry
1992
Q8296.In the Haber process for the manufacture of ammonia, the catalyst commonly used is finely divided
Avanadium
Bplatinum
Ciron
Dcopper
Correct Answer: C
The Haber process uses finely divided iron as a catalyst with potassium oxide and aluminium oxide as promoters.
JAMB (UTME)
Chemistry
1992
Q8297.A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as
Aan acidic oxide
Ban amphoteric oxide
Ca neutral oxide
Da basic oxide
Correct Answer: B
An oxide that reacts with both acids and bases to form salts is amphoteric.
JAMB (UTME)
Chemistry
1992
Q8298.Which of the following metals will liberate hydrogen from steam or dilute acid?
Acopper
Biron
Clead
Dmercury
Correct Answer: B
Iron is above hydrogen in the electrochemical series and can displace hydrogen from dilute acids and steam. Copper, lead, and mercury are below hydrogen.
JAMB (UTME)
Chemistry
1992
Q8299.Coal fire should not be used in poorly ventilated rooms because
Aof the accumulation of CO₂ which causes deep sleep
Bit is usually too hot
Cof the accumulation of CO which causes suffocation
Dit removes most of the gases in the room
Correct Answer: C
Incomplete combustion of coal produces carbon monoxide (CO), which is poisonous and causes suffocation.
JAMB (UTME)
Chemistry
1992
Q8300.The major component of the slag from the production of iron is
Aan alloy of calcium and iron
Bcoke
Cimpure iron
Dcalcium trioxosilicate (IV)
Correct Answer: D
In the blast furnace, limestone (CaCO₃) decomposes to CaO, which reacts with SiO₂ (sand) impurity to form calcium trioxosilicate(IV) (slag).