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Instruction
JAMB Chemistry 2017
JAMB (UTME)
Chemistry
2017
Q6801.If the electron configuration of an element is 1s² 2s² 2p⁵, how many unpaired electrons are there?
A2
B5
C1
D4
Correct Answer: C
The 2p sublevel has 5 electrons. According to Hund's rule, the first three electrons occupy separate orbitals with parallel spins. The remaining two electrons pair up in two of the orbitals. Therefore, there is 1 unpaired electron.
JAMB (UTME)
Chemistry
2017
Q6802.Which of the following gases can best be used for demonstrating the fountain experiment?
A(ii) and (iii)
B(i) and (iii)
C(ii) and (iv)
D(ii) only
Correct Answer: C
Ammonia (NH₃) and hydrogen chloride (HCl) are highly soluble in water and are used in the fountain experiment to demonstrate their high solubility.
JAMB (UTME)
Chemistry
2017
Q6803.The coloured nature of transition metal ions are associated with their partially filled
Af-orbital
Bs-orbital
Cp-orbital
Dd-orbital
Correct Answer: D
The colour of transition metal ions is due to electronic transitions within the partially filled d-orbitals (d-d transitions).
JAMB (UTME)
Chemistry
2017
Q6804.Which of the following separation processes is most likely to yield high quality ethanol (≥ 95%) from palm wine?
Afractional distillation without a dehydrant
Bsimple distillation with a dehydrant
Cfractional distillation with a dehydrant
Dcolumn chromatography
Correct Answer: A
Fractional distillation can yield up to 95% ethanol. To get higher purity, a dehydrant is needed. For 95%, fractional distillation without a dehydrant is sufficient.
JAMB (UTME)
Chemistry
2017
Q6805.The products formed on hydrolysis of CH₃COOCH₂CH₂CH₃ in acid (HCl) is
ACH₃COOH + CH₃CH₂CH₂Cl
BCH₃CH₂CH₂OH + CH₃COCl
CCH₃COOH + HOCH₂CH₂CH₃
DCH₃COOH + CH₃CH₃
Correct Answer: C
The ester CH₃COOCH₂CH₂CH₃ hydrolyses to ethanoic acid (CH₃COOH) and propan-1-ol (HOCH₂CH₂CH₃).
JAMB (UTME)
Chemistry
2017
Q6806.In the reaction: 3CuO + 2NH₃ → 3Cu + 3H₂O + N₂ how many electrons are transferred for each mole of copper produced?
A4.0 × 10⁻²³
B3.0 × 10⁻²³
C1.2 × 10²⁴
D6.0 × 10²⁴
Correct Answer: C
Cu²⁺ + 2e⁻ → Cu. Each mole of Cu produced requires 2 moles of electrons. 2 × 6.02 × 10²³ = 1.2 × 10²⁴ electrons.
JAMB (UTME)
Chemistry
2017
Q6807.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
2017
Q6808.8.0 g of an element X reacted with an excess of copper (II) tetraoxosulphate (VI) solution to deposit 21.3g of copper.
AX(s) + CuSO₄(aq) → Cu(s) + XSO₄(aq)
BX(s) + 2CuSO₄(aq) → 2Cu(s) + X(SO₄)₂(aq)
C2X(s) + CuSO₄(aq) → Cu(s) + X₂SO₄(aq)
D2X(s) + 3CuSO₄(aq) → 3Cu(s) + X₂(SO₄)₃(aq)
Correct Answer: A
Moles of Cu deposited = 21.3/64 = 0.333 mol. Moles of X = 8/M. For a 1:1 ratio (equation A), M = 8/0.333 = 24 (magnesium). This fits.
JAMB (UTME)
Chemistry
2017
Q6809.In the manufacture of iron in the blast furnace, iron (III) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions?
AThe coke is a powerful reducing agent and easily converts the iron oxide to iron.
BThe calcium carbonate reacts with SiO₂, an earthly impurity in the ore, to form calcium silicate
CThe coke will react with the iron produced to form steel
DThe calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity.
Correct Answer: D
Limestone (CaCO₃) decomposes to CaO, which then reacts with SiO₂ (sand) impurity to form calcium silicate (slag), which is removed.
JAMB (UTME)
Chemistry
2017
Q6810.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
2017
Q6811.A gas sample with an initial volume of 3.25dm³ is heated and allowed to expand to 9.75dm³ at constant pressure. What is the ratio of the final absolute temperature to the initial absolute temperature?
A3:1
B5:2
C5:4
D8:3
Correct Answer: A
Using Charles's law: V₁/T₁ = V₂/T₂. T₂/T₁ = V₂/V₁ = 9.75/3.25 = 3. So the ratio is 3:1.
JAMB (UTME)
Chemistry
2017
Q6812.The chemical used for coagulation in water purification is
Aaluminium tetraoxosulphate (VI)
Bcopper tetraoxosulphate (VI)
Csodium tetraoxosulphate (VI)
Dcalcium trioxocarbonate (IV)
Correct Answer: A
Aluminium tetraoxosulphate(VI) (alum, Al₂(SO₄)₃) is used as a coagulant in water purification to help fine particles clump together.
JAMB (UTME)
Chemistry
2017
Q6813.A liquid that will dissolve fat is
Ahydrochloric acid
Bcalcium hydroxide
Ckerosene
Dwater
Correct Answer: C
Kerosene is a non-polar organic solvent that can dissolve fats and oils. Water and aqueous solutions cannot dissolve fats effectively.
JAMB (UTME)
Chemistry
2017
Q6814.When air, which contains the gases: 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 oxygen. Quicklime (CaO) absorbs carbon dioxide and water vapour. The remaining gases are nitrogen and the rare gases.
JAMB (UTME)
Chemistry
2017
Q6815.The number of atoms in one mole of a substance is equal to
Athe atomic number
Bthe Avogadro number
Cthe gas constant
Dthe number of electrons.
Correct Answer: B
One mole of any substance contains Avogadro's number (6.02 × 10²³) of particles (atoms, molecules, ions, etc.).
JAMB (UTME)
Chemistry
2017
Q6816.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
2017
Q6817.The structural formula of ethanoic acid is
AH-COOH
BCH₃-COOH
CCH₃-CH₂-COOH
DCH₃-CH₂-CH₂-COOH
Correct Answer: B
Ethanoic acid (acetic acid) has the structural formula CH₃-COOH.
JAMB (UTME)
Chemistry
2017
Q6818.Environmental pollution is worsened by the release from automobile exhausts of
Awater vapour
Bsteam
Csmoke
Dheavy metals
Correct Answer: C
Automobile exhausts release smoke (particulate matter), which is a major air pollutant. They also release CO, NOx, and unburnt hydrocarbons.
JAMB (UTME)
Chemistry
2017
Q6819.What volume of 0.5 mol dm⁻³ H₂SO₄ will exactly neutralize 20 cm³ of 0.1 mol dm⁻³ NaOH solution?
Sodium acetate solution contains ions (Na⁺ and CH₃COO⁻) and conducts electricity, making it an electrolyte. Alcohol is a non-electrolyte. Solid KOH does not conduct. Mercury is a metal.
AAn increase in temperature and a decrease in the concentration of the reactants.
BA decrease in volume and an increase in the pressure of the reactants.
CA decrease in temperature and an increase in the concentration of the reactants.
DAn increase in temperature and an increase in the concentration of the reactants.
Correct Answer: D
Increasing temperature and increasing concentration of reactants both increase the rate of reaction.
JAMB (UTME)
Chemistry
2017
Q6822.Which of the following substances has the lowest vapour density?
AEthanoic acid
BPropanol
CDichloromethane
DEthanal.
Correct Answer: D
Vapour density is proportional to molecular mass. Ethanoic acid (60), propanol (60), dichloromethane (85), ethanal (44). Ethanal has the lowest molecular mass and hence the lowest vapour density.
JAMB (UTME)
Chemistry
2017
Q6823.The presence of an impurity in a substance will cause the melting point to
Abe zero
Breduce
Cincrease
Dbe stable
Correct Answer: B
The presence of an impurity lowers the melting point of a substance (melting point depression).
JAMB (UTME)
Chemistry
2017
Q6824.The process of converting linear alkanes to branched chain and cyclic hydrocarbons by heating in the presence of a catalyst to improve the quality of petrol is referred to as
Arefining
Bcracking
Creforming
Dblending
Correct Answer: C
Reforming is the process of converting straight-chain alkanes into branched-chain and cyclic hydrocarbons (aromatics) to improve the octane rating of petrol.
JAMB (UTME)
Chemistry
2017
Q6825.The petroleum fraction that is used in heating furnaces in industries is
Adiesel oil
Bgasoline
Ckerosene
Dlubricating oil
Correct Answer: A
Diesel oil is used in industrial heating furnaces and diesel engines. Gasoline is for cars, kerosene for lamps and jet fuel, and lubricating oil for lubrication.
JAMB (UTME)
Chemistry
2017
Q6826.The polymer used in making car rear lights is
APerspex
BBakelite
Cpolystyrene
Dpolyacrylonitrile
Correct Answer: D
Polyacrylonitrile (PAN) is used in making car rear lights because it is transparent, strong, and heat-resistant.
JAMB (UTME)
Chemistry
2017
Q6827.Due to the unstable nature of ethyne, it is stored by dissolving in
Aethane-1,2-diol
Bpropanol
Cethanoic acid
Dpropanone
Correct Answer: D
Ethyne is stored by dissolving it in propanone (acetone) under pressure. This is because ethyne is unstable and can explode if compressed alone.
JAMB (UTME)
Chemistry
2017
Q6828.The process of converting starch to ethanol is
Acracking
Bdistillation
Cfermentation
Doxidation
Correct Answer: C
Fermentation is the process by which starch is converted to ethanol using yeast (zymase enzyme).
JAMB (UTME)
Chemistry
2017
Q6829.The alkanol obtained from the production of soap is
Apropanol
Bethanol
Cglycerol
Dmethanol
Correct Answer: C
Saponification of fats and oils produces soap and glycerol (propane-1,2,3-triol).
JAMB (UTME)
Chemistry
2017
Q6830.A hydrocarbon has an empirical formula CH and a vapour density of 39. Determine its molecular formula. [C = 12, H = 1]
AC₂H₆
BC₃H₈
CC₃H₄
DC₆H₆
Correct Answer: D
Empirical formula mass = 12 + 1 = 13. Molecular mass = 2 × vapour density = 2 × 39 = 78. n = 78/13 = 6. Molecular formula = (CH)₆ = C₆H₆.
JAMB (UTME)
Chemistry
2017
Q6831.Polystyrene is widely used as packaging materials for fragile objects during transportation because of its
Alightness
Blow density
Chigh density
Dhigh compressibility
Correct Answer: B
Polystyrene foam has very low density and is an excellent shock absorber, making it ideal for packaging fragile objects.
JAMB (UTME)
Chemistry
2017
Q6832.Ethyne is passed through a hot tube containing organo-nickel catalyst to produce
AIsoprene
Bpolythene
Cethanol
Dbenzene
Correct Answer: D
Ethyne (acetylene) undergoes cyclization when passed through a hot tube containing an organo-nickel catalyst to produce benzene.
JAMB (UTME)
Chemistry
2017
Q6833.The bleaching action of chlorine is effective due to the presence of
AHydrogen chloride
BWater
CAir
DOxygen
Correct Answer: B
Chlorine bleaches by oxidation in the presence of water. It reacts with water to form hypochlorous acid (HOCl), which is the active bleaching agent.
Instruction
JAMB Chemistry 2018
JAMB (UTME)
Chemistry
2018
Q6834.The periodic classification of the elements is an arrangement of the elements in order of their
Aatomic weights
Bisotopic weights
Cmolecular weights
Datomic numbers
Correct Answer: D
The modern periodic table arranges elements in order of increasing atomic number. This is the fundamental basis of the modern periodic law.
JAMB (UTME)
Chemistry
2018
Q6835.If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water, and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be
A2.2 M
B1.1 M
C0.22 M
D0.11 M
Correct Answer: C
Using dilution formula: M₁V₁ = M₂V₂. M₁ = 2.2 M, V₁ = 1 L, V₂ = 1 + 10 = 11 L. M₂ = (2.2 × 1)/11 = 0.22 M.
JAMB (UTME)
Chemistry
2018
Q6836.In the above experiment (Fig. 1) the litmus paper will initially
Abe bleached
Bturn green
Cturn red
Dturn blue
Correct Answer: D
The experiment shows the decomposition of ammonium chloride. The gases produced are NH₃ (basic) and HCl (acidic). The lighter NH₃ gas reaches the litmus paper first, turning it blue.
JAMB (UTME)
Chemistry
2018
Q6837.A correct electrochemical series can be obtained from K, Na, Ca, Al, Mg, Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging
AAl and Mg
BZn and Fe
CZn and Pb
DPb and H
Correct Answer: A
The correct order of reactivity is K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au. Al and Mg should be interchanged (Mg is more reactive than Al).
JAMB (UTME)
Chemistry
2018
Q6838.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
2018
Q6839.On which of the following is the solubility of a gaseous substance dependent?
AI, II, III and IV
BI and II only
CII only
DI, III and IV only
Correct Answer: A
The solubility of a gas depends on the nature of the solvent, nature of the solute, temperature, and pressure.
JAMB (UTME)
Chemistry
2018
Q6840.Which of the following statements is correct about the periodic table?
AElements in the same period have the same number of valence electrons
BThe valence electrons of the elements in the same period increase progressively across the period.
CElements in the same group have the same number of electron shells
DThe non-metallic properties of the elements tend to decrease across each period.
Correct Answer: B
Across a period, the number of valence electrons increases progressively. Elements in the same group have the same number of valence electrons, not shells. Non-metallic properties increase across a period.
JAMB (UTME)
Chemistry
2018
Q6841.The boiling of fat and aqueous caustic soda is referred to as
Ahydrolysis
Besterification
Cacidification
Dsaponification
Correct Answer: D
Saponification is the hydrolysis of fats and oils with an alkali (caustic soda) to produce soap and glycerol.
JAMB (UTME)
Chemistry
2018
Q6842.Which of the following pairs of substances will react further with oxygen to form a higher oxide?
ACO₂ and H₂O
BNO and H₂O
CCO and CO₂
DSO₂ and NO
Correct Answer: D
SO₂ can be oxidized to SO₃, and NO can be oxidized to NO₂. CO₂ and H₂O are already fully oxidized.
JAMB (UTME)
Chemistry
2018
Q6843.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
Dlowering the energy barrier of the reaction.
Correct Answer: D
A catalyst speeds up a reaction by providing an alternative pathway with a lower activation energy (energy barrier).
JAMB (UTME)
Chemistry
2018
Q6844.Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of sand, water and methanoic acid?
AFractional distillation
BFiltration followed by distillation
CNeutralization with sodium hydroxide followed by distillation
DNeutralization with sodium hydroxide followed by filtration
Correct Answer: A
Fractional distillation is used to separate miscible liquids with different boiling points. Since methanoic acid and water have similar boiling points, fractional distillation is the most suitable method.
JAMB (UTME)
Chemistry
2018
Q6845.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?
A2.7 g
B1.2 g
C0.9 g
D0.3 g
Correct Answer: D
Equivalent mass of Ag = 108/1 = 108. Equivalent mass of Al = 27/3 = 9. Mass of Al = (3.6/108) × 9 = 0.3 g.
JAMB (UTME)
Chemistry
2018
Q6846.Suitable reagents for the laboratory preparation of nitrogen are
Asodium dioxonitrate (III) and ammonium chloride
Bsodium trioxonitrate (V) and ammonium chloride
Csodium chloride and ammonium trioxonitrate (V)
Dsodium chloride and ammonium dioxonitrate (III).
Correct Answer: A
Nitrogen is prepared in the laboratory by heating a mixture of sodium dioxonitrate(III) (NaNO₂) and ammonium chloride (NH₄Cl).
JAMB (UTME)
Chemistry
2018
Q6847.The number of electrons in the valence shell of an element of atomic number 14 is
A1
B2
C3
D4
Correct Answer: D
Atomic number 14 is silicon (Si). Its electronic configuration is 1s² 2s² 2p⁶ 3s² 3p². It has 4 valence electrons.
JAMB (UTME)
Chemistry
2018
Q6848.What volume of oxygen will remain after reacting 8cm³ of hydrogen gas with 20cm³ of oxygen gas?