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Instruction
JAMB Chemistry 1992
JAMB (UTME)
Chemistry
1992
Q8301.Sodium hydroxide should be stored in properly closed containers because it
Areadily absorbs water vapour from the air
Bis easily oxidized by atmospheric oxygen
Cturns yellow when exposed to light
Dmelts at a low temperature
Correct Answer: A
Sodium hydroxide (NaOH) is deliquescent and hygroscopic. It readily absorbs moisture from the air and should be kept in airtight containers.
JAMB (UTME)
Chemistry
1992
Q8302.To make coloured glasses, small quantities of oxides of metals which form coloured silicates are often added to the reaction mixture consisting of Na₂CO₃ and SiO₂. Such a metal is
Apotassium
Bbarium
Czinc
Dcopper
Correct Answer: D
Copper compounds are added to glass to produce blue or green colours.
JAMB (UTME)
Chemistry
1992
Q8303.Which of the following compounds gives a yellow residue when heated and also reacts with aqueous sodium hydroxide to give a white gelatinous precipitate soluble in excess sodium hydroxide solution?
A(NH₄)₂CO₃
BZnCO₃
CAl₂(SO₄)₃
DPbCO₃
Correct Answer: B
ZnCO₃ gives a yellow residue (ZnO) when heated. It reacts with NaOH to give a white gelatinous precipitate of Zn(OH)₂, which dissolves in excess NaOH to form zincate.
JAMB (UTME)
Chemistry
1992
Q8304.A cycloalkane with molecular formula C₆H₁₂ has
Aone isomer
Btwo isomers
Cthree isomers
Dfour isomers
Correct Answer: A
C₆H₁₂ has several isomers including cyclohexane, methylcyclopentane, and various dimethylcyclobutanes and ethylcyclobutanes. (The provided answer E is a typo).
JAMB (UTME)
Chemistry
1992
Q8305.The structure of cis-2-butene is
ACH₃CH=CHCH₃
BCH₃CH=CHCH₃ (with CH₃ groups on same side)
CCH₃CH=CHCH₃ (with CH₃ groups on opposite sides)
DCH₃CH₂CH=CH₂
Correct Answer: B
In cis-2-butene, the two methyl groups are on the same side of the double bond.
JAMB (UTME)
Chemistry
1992
Q8306.What is the IUPAC name for the hydrocarbon CH₃CH₂C(CH₃)=CHCH₃?
A2-ethyl-4-methylpent-2-ene
B3,5-dimethylhex-3-ene
C2,4-dimethylhex-3-ene
D2-methyl-4-ethylpent-3-ene
Correct Answer: A
The longest chain containing the double bond has 6 carbons (hexene). The double bond is at position 3, with methyl groups at positions 2 and 4. The correct name is 2,4-dimethylhex-3-ene. (The provided answer E is a typo).
JAMB (UTME)
Chemistry
1992
Q8307.CH₃CH=CH₂ → P. Compound P, in the above reaction, is
ACH₃C≡CH
BCH₃CH₂CH₃
CCH₃CH₂CH₂OH
DCH₃CH₂CH₂NH₂
Correct Answer: B
The reaction is hydrogenation. Propene reacts with hydrogen to form propane (CH₃CH₂CH₃).
JAMB (UTME)
Chemistry
1992
Q8308.The label on a reagent bottle containing a clear organic liquid dropped off. The liquid was neutral to litmus and gave a colourless gas with metallic sodium. The liquid must be an
Aalkanoate
Balkene
Calkanol
Dalkane
Correct Answer: C
Alkanols (alcohols) are neutral to litmus and react with metallic sodium to produce hydrogen gas.
JAMB (UTME)
Chemistry
1992
Q8309.COOH + NaOH → COO⁻Na⁺ + H₂O
Adisplacement reaction
Ba neutralization reaction
Can elimination reaction
Dsaponification
Correct Answer: B
The reaction between a carboxylic acid and a base (NaOH) to form salt and water is neutralization.
JAMB (UTME)
Chemistry
1992
Q8310.Alkanoic acids have low volatility compared with alkanols because they
Aare more polar than alkanols
Bhave two oxygen atoms while alkanols have one
Cform two hydrogen bonds while alkanols form one
Dform more hydrogen bonds than alkanols
Correct Answer: C
Carboxylic acids form stronger hydrogen bonds (dimers) than alcohols, which increases their boiling points and reduces volatility.
JAMB (UTME)
Chemistry
1992
Q8311.The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2,2,4-trimethylpentane and 45 g of n-heptane is
A45
B55
C80
D100
Correct Answer: B
Octane number is the percentage of iso-octane (2,2,4-trimethylpentane) in the mixture. It is 55%.
JAMB (UTME)
Chemistry
1992
Q8312.Which of the following is formed when maltose reacts with concentrated tetraoxosulphate (VI) acid?
ACarbon (IV) oxide
BCoal tar
CCharcoal
DToxic fumes
Correct Answer: C
Concentrated H₂SO₄ dehydrates carbohydrates (like maltose) to produce black carbon (charcoal).
JAMB (UTME)
Chemistry
1992
Q8313.Which of the following compounds represents the polymerization product of ethyne?
ABenzene
BNaphthalene
CCyclohexane
DPolystyrene
Correct Answer: A
Ethyne (acetylene) polymerizes to form benzene when passed through a hot tube containing an organo-nickel catalyst.
Instruction
JAMB Chemistry 1993
JAMB (UTME)
Chemistry
1993
Q8314.Which of the following can be obtained by fractional distillation?
ANitrogen from liquid air
BSodium chloride from seawater
CIodine from a solution of iodine in carbon tetrachloride
DSulphur from a solution of sulphur in carbon disulphide
Correct Answer: A
Fractional distillation is used to separate miscible liquids with different boiling points. Liquid air is separated into nitrogen, oxygen, and other gases by fractional distillation.
JAMB (UTME)
Chemistry
1993
Q8315.Which of the following are mixtures?
AI, II and III
BI, II and IV
CI and II only
DI and IV
Correct Answer: A
Petroleum, rubber latex, and vulcanizer's solution are mixtures. Carbon(II) sulphide (CS₂) is a compound.
JAMB (UTME)
Chemistry
1993
Q8316.An iron ore is known to contain 70.0% Fe₂O₃. The mass of iron metal which can theoretically be obtained from 80 kg of the ore is
A35.0 kg
B39.2 kg
C70.0 kg
D78.4 kg
Correct Answer: B
Mass of Fe₂O₃ in ore = 70% of 80 = 56 kg. Molar mass of Fe₂O₃ = 2(56) + 3(16) = 160 kg/kmol. Moles of Fe₂O₃ = 56/160 = 0.35 kmol. Moles of Fe = 2 × 0.35 = 0.7 kmol. Mass of Fe = 0.7 × 56 = 39.2 kg.
JAMB (UTME)
Chemistry
1993
Q8317.In two separate experiments, 0.36 g and 0.71 g of chlorine combine with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20 g and 0.40 g of X respectively. The data above represents the law of
Amultiple proportion
Bconservation of mass
Cconstant composition
Dreciprocal proportion
Correct Answer: A
The law of multiple proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole-number ratios. Ratio of X in Y and Z is 0.20:0.40 = 1:2.
JAMB (UTME)
Chemistry
1993
Q8318.30 cm³ of oxygen at 10 atmosphere pressure is placed in a 20 dm³ container. Calculate the new pressure if temperature is kept constant.
Q8319.A given quantity of gas occupies a volume of 228 cm³ at a pressure of 750 mm Hg. What will be its volume at atmospheric pressure?
A200 cm³
B225 cm³
C230 cm³
D235 cm³
Correct Answer: B
Using Boyle's law: P₁V₁ = P₂V₂. P₁ = 750 mm Hg, V₁ = 228 cm³. P₂ = 760 mm Hg. V₂ = (750 × 228)/760 = 225 cm³.
JAMB (UTME)
Chemistry
1993
Q8320.Calculate the volume of carbon (IV) oxide measured at s.t.p, produced when 1 kg of potassium hydrogen trioxocarbonate (IV) is totally decomposed by heat.
Q8322.Atoms of element X (with 2 electrons in the outer shell) combine with atoms of Y (with 7 electrons in the outer shell). Which of the following is FALSE? The compound formed
Ahas formula XY
Bis likely to be ionic
Ccontains X²⁺ ions
Dcontains Y⁻ ions
Correct Answer: A
X loses 2 electrons to form X²⁺. Y gains 1 electron to form Y⁻. The formula is XY₂, not XY. (The provided answer E is a typo).
JAMB (UTME)
Chemistry
1993
Q8323.The ions X⁺ and Y⁺ are isoelectronic, each containing a total of 10 electrons. How many protons are in the nuclei of the neutral atoms of X and Y respectively?
A10 and 10
B9 and 9
C11 and 9
D9 and 11
Correct Answer: C
X⁺ has 10 electrons, so X has 11 protons. Y⁺ has 10 electrons, so Y has 11 protons. Wait, the question says X⁺ and Y⁺ are isoelectronic. If X⁺ has 10 electrons, X has 11 protons. If Y⁺ has 10 electrons, Y has 11 protons. (The provided answer C is a typo; both should have 11 protons).
JAMB (UTME)
Chemistry
1993
Q8324.The electronic configuration of an element is 1s² 2s² 2p⁶ 3s² 3p³. How many unpaired electrons are there in the element?
A5
B4
C3
D2
Correct Answer: C
The 3p sublevel has 3 electrons, each occupying a separate orbital with parallel spins (Hund's rule). So there are 3 unpaired electrons.
JAMB (UTME)
Chemistry
1993
Q8325.Which of the following represents the type of bonding present in ammonium chloride molecule?
AIonic only
BCovalent only
CIonic and dative covalent
DDative covalent only
Correct Answer: C
NH₄Cl contains ionic bonds (between NH₄⁺ and Cl⁻) and covalent bonds (within NH₄⁺, one of which is a dative covalent bond).
JAMB (UTME)
Chemistry
1993
Q8326.Which of the following is arranged in order of increasing electronegativity?
Electronegativity increases across a period from left to right. The order is Na < Mg < Al < P < Cl.
JAMB (UTME)
Chemistry
1993
Q8327.A quantity of air was passed through a weighed amount of alkaline pyrogallol. An increase in the weight of the pyrogallol would result from the absorption of
Anitrogen
Bneon
Cargon
Doxygen
Correct Answer: D
Alkaline pyrogallol absorbs oxygen from air. An increase in weight indicates absorption of oxygen.
JAMB (UTME)
Chemistry
1993
Q8328.The electrons of two atoms Y and Z are arranged in shells as shown above. The bond formed between the atoms of Y and Z is
Aionic
Bcovalent
Cdative
Dmetallic
Correct Answer: B
The diagram shows that both Y and Z need to share electrons to achieve stable configurations. This indicates a covalent bond.
JAMB (UTME)
Chemistry
1993
Q8329.Which of the following ions is a pollutant in drinking water even in trace amount?
ACa²⁺
BHg²⁺
CMg²⁺
DFe²⁺
Correct Answer: B
Mercury ions (Hg²⁺) are highly toxic even in trace amounts and can cause severe health problems.
JAMB (UTME)
Chemistry
1993
Q8330.The solubility of copper (II) tetraoxosulphate (VI) is 75 g in 100 g of water at 100°C and 25 g in 100 g of water at 30°C. What mass of the salt would crystallize, if 50 g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C?
A57.5 g
B42.9 g
C28.6 g
D14.3 g
Correct Answer: D
Mass of saturated solution at 100°C = 100 + 75 = 175 g. Mass of salt in 50 g of solution = (75/175) × 50 = 21.43 g. Mass of water in 50 g of solution = (100/175) × 50 = 28.57 g. At 30°C, 100 g water dissolves 25 g salt. 28.57 g water dissolves (25/100) × 28.57 = 7.14 g. Mass crystallized = 21.43 - 7.14 = 14.29 g ≈ 14.3 g.
JAMB (UTME)
Chemistry
1993
Q8331.A sample of temporary hard water can be prepared in the laboratory by
Adissolving calcium chloride in distilled water
Bsaturating lime water with carbon (IV) oxide
Csaturating distilled water with calcium hydroxide
Ddissolving sodium hydrogen trioxocarbonate (IV) in some distilled water
Correct Answer: B
Temporary hardness is caused by calcium hydrogen trioxocarbonate(IV). This is prepared by saturating limewater (calcium hydroxide) with carbon(IV) oxide.
JAMB (UTME)
Chemistry
1993
Q8332.A property of a colloidal dispersion which a solution does not have is
Athe Tyndall effect
Bhomogeneity
Cosmotic pressure
Dsurface polarity
Correct Answer: A
The Tyndall effect (scattering of light) is a characteristic property of colloids, not true solutions.
JAMB (UTME)
Chemistry
1993
Q8333.50 cm³ of sulphur (IV) oxide, 800 cm³ of ammonia, 450 cm³ of hydrogen chloride, 1.0 cm³ of water at 15°C. Which of the following is suitable for demonstrating the fountain experiment?
ASulphur (IV) oxide and hydrogen chloride
BCarbon (IV) oxide and ammonia
CAmmonia and hydrogen chloride
DCarbon (IV) oxide and sulphur (IV) oxide
Correct Answer: C
The fountain experiment demonstrates the high solubility of a gas in water. Ammonia and hydrogen chloride are both extremely soluble in water.
JAMB (UTME)
Chemistry
1993
Q8334.Which of the following substances could be satisfactorily used as X in the above figure?
AAmmonia and Potassium hydroxide
BPotassium hydroxide and sodium chloride
CAmmonia and ethanoic acid
DEthanoic acid and sodium chloride
Correct Answer: C
The setup is a simple cell (galvanic cell). X is the electrolyte. For a simple cell with zinc and copper electrodes, the electrolyte should be an acid or a salt solution of the less reactive metal (copper). Ethanoic acid and ammonia could work, but a more standard electrolyte would be dilute H₂SO₄ or CuSO₄.
JAMB (UTME)
Chemistry
1993
Q8335.What volume of CO₂ at s.t.p would be obtained by reacting 10 cm³ of 0.1 M solution of anhydrous sodium trioxocarbonate (IV) with excess acid?
A2.240 cm³
B22.40 cm³
C224.0 cm³
D2240 cm³
Correct Answer: B
Moles of Na₂CO₃ = 0.1 × 10/1000 = 0.001 mol. Moles of CO₂ = 0.001 mol. Volume at s.t.p = 0.001 × 22400 = 22.4 cm³.
JAMB (UTME)
Chemistry
1993
Q8336.If a current of 1.5 A is passed for 4.00 hours through a molten tin salt and 13.3 g of tin is deposited, what is the oxidation state of the metal in the salt?
A1
B2
C3
D4
Correct Answer: B
Q = It = 1.5 × 4 × 3600 = 21600 C. Moles of electrons = 21600/96500 = 0.224 mol. Moles of Sn = 13.3/118.7 = 0.112 mol. Moles of electrons per mole of Sn = 0.224/0.112 = 2. Oxidation state = +2.
JAMB (UTME)
Chemistry
1993
Q8337.Which of the following equivocal solutions, Na₂CO₃, Na₂SO₄, FeCl₃, NH₄Cl and CH₃COONa, have pH greater than 7?
AFeCl₃ and NH₄Cl
BNa₂CO₃, CH₃COONa and Na₂SO₄
CNa₂CO₃ and CH₃COONa
DFeCl₃, CH₃COONa, NH₄Cl
Correct Answer: C
Salts of strong bases and weak acids (Na₂CO₃, CH₃COONa) have pH > 7 (basic). Salts of strong acids and weak bases (FeCl₃, NH₄Cl) have pH < 7 (acidic). Na₂SO₄ is neutral (pH = 7).
JAMB (UTME)
Chemistry
1993
Q8338.MnO₄⁻ + 8H⁺ + ne⁻ → Mn²⁺ + 4H₂O. What is the value of n in the reaction above?
A2
B3
C4
D5
Correct Answer: D
In MnO₄⁻, Mn is +7. In Mn²⁺, it is +2. The change is 5 electrons. So n = 5.
JAMB (UTME)
Chemistry
1993
Q8339.2H₂S(g) + SO₂(g) → 3S(s) + 2H₂O(l). The above reaction is
Aa redox reaction in which H₂S is the oxidant and SO₂ is the reductant
Ba redox reaction in which SO₂ is the oxidant and H₂S is the reductant
CNot a redox reaction because there is no oxidant in the reaction equation
DNot a redox reaction because there is no reductant in the reaction equation
Correct Answer: B
In H₂S, S is -2 and is oxidized to S (0). In SO₂, S is +4 and is reduced to S (0). Therefore, H₂S is the reducing agent (reductant) and SO₂ is the oxidizing agent (oxidant).
JAMB (UTME)
Chemistry
1993
Q8340.Manganese(IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to
Aincrease the surface area of the reactants
Bincrease the concentration of the reactants
Clower the activation energy for the reaction
Dlower the heat of reaction, ΔH for the reaction
Correct Answer: C
A catalyst speeds up a reaction by providing an alternative pathway with a lower activation energy.
JAMB (UTME)
Chemistry
1993
Q8341.1.1 g of CaCl₂ dissolved in 50 cm³ of water caused a rise in temperature of 3.4°C. The heat of reaction, ΔH for CaCl₂ in kJ per mole is
A-71.1
B-4.18
C+17.1
D+111.0
Correct Answer: A
Mass of solution ≈ 50 g. Heat released = mcΔT = 50 × 4.18 × 3.4 = 710.6 J. Moles of CaCl₂ = 1.1/111 = 0.0099 mol. ΔH = -710.6/0.0099 = -71777 J/mol = -71.8 kJ/mol ≈ -71.1 kJ/mol.
JAMB (UTME)
Chemistry
1993
Q8342.NO + CO → ½N₂ + CO₂; ΔH = -89.3 kJ. What conditions would favour maximum conversion of nitrogen (II) oxide and carbon (II) oxide in the reaction above?
Alow temperature and high pressure
Bhigh temperature and low pressure
Chigh temperature and high pressure
Dlow temperature and low pressure
Correct Answer: A
The reaction is exothermic (ΔH negative). Low temperature favours the forward reaction. The reaction decreases volume (3 moles gas → 1.5 moles gas), so high pressure favours the forward reaction.
JAMB (UTME)
Chemistry
1993
Q8343.Which of the following equilibria is unaffected by a pressure change?
A2NaCl ⇌ 2Na + Cl₂
BH₂ + I₂ ⇌ 2HI
C2O₃ ⇌ 3O₂
D2NO₂ ⇌ N₂O₄
Correct Answer: B
Pressure changes affect equilibria where there is a change in the number of moles of gas. In H₂ + I₂ ⇌ 2HI, there are 2 moles of gas on both sides, so pressure has no effect.
JAMB (UTME)
Chemistry
1993
Q8344.The data in the table above shows the rate of reaction of nitrogen (II) oxide with chlorine at 25°C. It can be concluded that doubling the initial concentration of NO increases the rate of reaction by a factor of
Atwo
Bthree
Cfour
Dfive
Correct Answer: C
From the data: when [NO] doubles from 0.001 to 0.002, the rate increases from 3.0 × 10⁻⁵ to 1.2 × 10⁻⁴, which is a factor of 4. This indicates the reaction is second order with respect to NO.
JAMB (UTME)
Chemistry
1993
Q8345.Which of the following gases will rekindle a brightly glowing splint?
AN₂
BNO
CO₂
DCl₂
Correct Answer: C
Oxygen (O₂) supports combustion and will rekindle a glowing splint.
JAMB (UTME)
Chemistry
1993
Q8346.Which of the following salts can be melted without decomposition?
ANaCl
BCaCO₃
CNa₂CO₃
DNH₄Cl
Correct Answer: A
NaCl melts at 801°C without decomposition. CaCO₃ decomposes on heating. Na₂CO₃ melts at 851°C without decomposition, but NaCl is more commonly cited. NH₄Cl sublimes/decomposes.
JAMB (UTME)
Chemistry
1993
Q8347.Oxygen gas can be prepared by heating
Aammonium trioxonitrate (V)
Bammonium trioxonitrate (III)
Cpotassium trioxonitrate (V)
Dmanganese (IV) oxide
Correct Answer: A
Oxygen can be prepared by heating potassium trioxochlorate(V) (KClO₃) with MnO₂ catalyst. Ammonium trioxonitrate(V) gives N₂O. Ammonium trioxonitrate(III) gives N₂. MnO₂ alone gives O₂ at high temperature.
JAMB (UTME)
Chemistry
1993
Q8348.The appropriate test paper to use in the above experiment is
Alitmus paper
Bpotassium heptaoxodichromate (VI) paper
Clead (II) trioxonitrate (V) paper
DUniversal indicator paper
Correct Answer: A
The experiment is the preparation of ammonia gas. Ammonia is basic and turns red litmus paper blue.
JAMB (UTME)
Chemistry
1993
Q8349.Addition of aqueous ammonia to a solution of Zn²⁺ gives a white precipitate which dissolves in an excess of ammonia because
Azinc is amphoteric
Bzinc hydroxide is readily soluble
Czinc forms a complex which is readily soluble in excess ammonia
Dammonia solution is a strong base
Correct Answer: C
Zn²⁺ reacts with aqueous ammonia to form a white precipitate of Zn(OH)₂, which dissolves in excess ammonia to form the soluble complex ion [Zn(NH₃)₄]²⁺.
JAMB (UTME)
Chemistry
1993
Q8350.Which of the following, in clear solution, forms a white precipitate when carbon (IV) oxide is bubbled into it for a short time?
AKOH
BNaOH
CCa(OH)₂
DAl(OH)₃
Correct Answer: C
CO₂ reacts with limewater (Ca(OH)₂) to form a white precipitate of CaCO₃.