JAMB Past Questions

JAMB Chemistry 2002
Questions & Answers

40 questions · Correct answers highlighted · 40 with explanations

40 Total Questions
2002 Exam Year
40 With Explanations
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1
Question 1 of 40
JAMB · Chemistry · 2002

The IUPAC name of the compound CH₃CH(CH₃)CH₂CH₃ is

A. 2-methylbutane
B. 3-methylbutane
C. 2-methylpentane
D. 3-methylpentane
Explanation

The longest chain has 4 carbons (butane); a methyl group is on carbon 2, so it’s 2-methylbutane.

2
Question 2 of 40
JAMB · Chemistry · 2002

Which of the following is used as fuel in miners’ lamps?

A. Ethanal
B. Ethyne
C. Ethene
D. Ethane
Explanation

Ethyne (acetylene) burns with a bright flame, suitable for miners’ lamps.

3
Question 3 of 40
JAMB · Chemistry · 2002

Benzene reacts with hydrogen in the presence of a nickel catalyst at 180°C to form

A. xylene
B. toluene
C. cyclopentane
D. cyclohexane
Explanation

Benzene undergoes hydrogenation to form cyclohexane (C₆H₁₂).

4
Question 4 of 40
JAMB · Chemistry · 2002

Which gas hastens the ripening of fruits?

A. Ethene
B. Ethanol
C. Ethyne
D. Ethane
Explanation

Ethene (ethylene) is a plant hormone that promotes fruit ripening.

5
Question 5 of 40
JAMB · Chemistry · 2002

The final products of complete chlorination of methane in the presence of ultraviolet light are

A. trichloromethane and HCl
B. dichloromethane and HCl
C. tetrachloromethane and HCl
D. chloromethane and HCl
Explanation

With excess chlorine, methane forms tetrachloromethane (CCl₄) and HCl.

6
Question 6 of 40
JAMB · Chemistry · 2002

The correct order of increasing boiling points for C₃H₇OH, C₇H₁₆, and C₄H₁₀ is

A. C₃H₇OH < C₇H₁₆ < C₄H₁₀
B. C₄H₁₀ < C₇H₁₆ < C₃H₇OH
C. C₇H₁₆ < C₃H₇OH < C₄H₁₀
D. C₄H₁₀ < C₃H₇OH < C₇H₁₆
Explanation

Boiling points: C₄H₁₀ (-0.5°C), C₇H₁₆ (98°C), C₃H₇OH (97°C, higher due to hydrogen bonding).

7
Question 7 of 40
JAMB · Chemistry · 2002

The haloalkane commonly used in dry cleaning is

A. chloromethane
B. trichloromethane
C. tetrachloroethene
D. dichloromethane
Explanation

Tetrachloroethene (C₂Cl₄) is a solvent used in dry cleaning.

8
Question 8 of 40
JAMB · Chemistry · 2002

A hydrocarbon Y treated with bromine water does not decolorize it. Y belongs to

A. benzene
B. alkynes
C. alkenes
D. alkanes
Explanation

Alkanes do not react with bromine water; alkenes and alkynes decolorize it.

9
Question 9 of 40
JAMB · Chemistry · 2002

The compound historically used as an anaesthetic is

A. CCl₄
B. CHCl₃
C. CH₂Cl₂
D. CH₃Cl
Explanation

Chloroform (CHCl₃) was used as an anaesthetic.

10
Question 10 of 40
JAMB · Chemistry · 2002

A major use of alkanes is

A. as domestic and industrial fuel
B. in hydrogenation of oils
C. in textile production
D. in plastic manufacturing
Explanation

Alkanes like methane and propane are widely used as fuels.

11
Question 11 of 40
JAMB · Chemistry · 2002

The oxidation number of sulphur in H₂SO₄ is

A. +2
B. +4
C. +6
D. +8
Explanation

H (+1), O (-2); 2(+1) + S + 4(-2) = 0; S = +6.

12
Question 12 of 40
JAMB · Chemistry · 2002

Which of the following is a physical change?

A. Burning of wood
B. Rusting of iron
C. Melting of ice
D. Fermentation of sugar
Explanation

Melting of ice is reversible and involves no chemical change.

13
Question 13 of 40
JAMB · Chemistry · 2002

The molarity of a solution containing 4.0 g of NaOH in 250 cm³ is [Na = 23, O = 16, H = 1]

A. 0.1 M
B. 0.4 M
C. 0.8 M
D. 1.6 M
Explanation

Molar mass NaOH = 40 g/mol; moles = 4/40 = 0.1 mol; volume = 0.25 L; M = 0.1/0.25 = 0.4 M.

14
Question 14 of 40
JAMB · Chemistry · 2002

The gas responsible for acid rain is

A. carbon monoxide
B. nitrogen monoxide
C. sulphur dioxide
D. hydrogen sulphide
Explanation

Sulphur dioxide forms sulphurous and sulphuric acids in rain.

15
Question 15 of 40
JAMB · Chemistry · 2002

The shape of a CH₄ molecule is

A. linear
B. trigonal planar
C. tetrahedral
D. octahedral
Explanation

CH₄ has four bonding pairs, forming a tetrahedral shape.

16
Question 16 of 40
JAMB · Chemistry · 2002

Which of the following is an electrolyte?

A. Alcohol
B. Sugar solution
C. Sodium chloride solution
D. Distilled water
Explanation

NaCl dissociates into ions, conducting electricity.

17
Question 17 of 40
JAMB · Chemistry · 2002

The main source of organic compounds is

A. mineral oil
B. coal
C. petroleum
D. natural gas
Explanation

Petroleum is the primary source of hydrocarbons.

18
Question 18 of 40
JAMB · Chemistry · 2002

The pH of a neutral solution at 25°C is

A. 0
B. 7
C. 14
D. 1
Explanation

At 25°C, [H⁺] = [OH⁻] = 10⁻⁷ M, so pH = 7.

19
Question 19 of 40
JAMB · Chemistry · 2002

The gas that bleaches green leaves is

A. carbon dioxide
B. chlorine
C. sulphur dioxide
D. nitrogen dioxide
Explanation

Chlorine oxidizes chlorophyll, causing bleaching.

20
Question 20 of 40
JAMB · Chemistry · 2002

The type of bond in ammonium chloride (NH₄Cl) is

A. ionic only
B. covalent only
C. ionic, covalent, and coordinate
D. ionic and covalent
Explanation

NH₄Cl has ionic (NH₄⁺, Cl⁻), covalent (N-H), and coordinate (N→H) bonds.

21
Question 21 of 40
JAMB · Chemistry · 2002

The compound 2-chlorobutane exhibits

A. geometric isomerism
B. optical isomerism
C. structural isomerism
D. positional isomerism
Explanation

2-Chlorobutane has a chiral carbon, showing optical isomerism.

22
Question 22 of 40
JAMB · Chemistry · 2002

An organic compound has an empirical formula CH₂O and vapour density of 45. What is its molecular formula? [C = 12, H = 1, O = 16]

A. C₃H₇OH
B. C₂H₅OH
C. C₃H₆O₃
D. C₂H₄O₂
Explanation

Molar mass = 2 × 45 = 90; (CH₂O)₃ = C₃H₆O₃ (90 g/mol).

23
Question 23 of 40
JAMB · Chemistry · 2002

The reaction C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + energy produces

A. propanol
B. butanol
C. methanol
D. ethanol
Explanation

Fermentation of glucose produces ethanol (C₂H₅OH).

24
Question 24 of 40
JAMB · Chemistry · 2002

The number of isomers of C₄H₁₀ is

A. 1
B. 2
C. 3
D. 4
Explanation

C₄H₁₀ has two isomers: n-butane and isobutane.

25
Question 25 of 40
JAMB · Chemistry · 2002

The functional groups in 2-chloroethanol (ClCH₂CH₂OH) are

A. alkene and chloro-group
B. hydroxyl and chloro-group
C. alkene and hydroxyl
D. chloro-group and alkane
Explanation

2-Chloroethanol has -OH (hydroxyl) and -Cl (chloro) groups.

26
Question 26 of 40
JAMB · Chemistry · 2002

Which of the following is a primary amine?

A. (CH₃)₃N
B. CH₃NH₂
C. (CH₃)₂NH
D. C₆H₅NH₂
Explanation

CH₃NH₂ has one alkyl group, making it a primary amine.

27
Question 27 of 40
JAMB · Chemistry · 2002

An organic compound K forms a red precipitate with Fehling’s solution, unlike compound L. K is an

A. alkanol
B. alkane
C. alkanal
D. alkanone
Explanation

Alkanals (aldehydes) reduce Fehling’s solution, forming a red precipitate.

28
Question 28 of 40
JAMB · Chemistry · 2002

Which statement is true about 2-methylpropane and butane?

A. They belong to the same homologous series
B. They have the same boiling point
C. They have different numbers of carbon atoms
D. They have different chemical properties
Explanation

Both are C₄H₁₀, belonging to the alkane homologous series.

29
Question 29 of 40
JAMB · Chemistry · 2002

The reaction CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O is

A. esterification
B. condensation
C. saponification
D. neutralization
Explanation

Acid + alcohol forms an ester and water, known as esterification.

30
Question 30 of 40
JAMB · Chemistry · 2002

The process of converting starch to ethanol involves

A. cracking
B. fermentation
C. distillation
D. esterification
Explanation

Starch is hydrolyzed to glucose, then fermented to ethanol.

31
Question 31 of 40
JAMB · Chemistry · 2002

Which metal is the most reactive?

A. Zinc
B. Iron
C. Potassium
D. Copper
Explanation

Potassium is highest in the reactivity series.

32
Question 32 of 40
JAMB · Chemistry · 2002

The empirical formula of a hydrocarbon with molecular formula C₆H₁₄ is

A. CH₂
B. C₃H₇
C. C₂H₇
D. CH₃
Explanation

C₆H₁₄ ÷ 2 = C₃H₇ (simplest ratio).

33
Question 33 of 40
JAMB · Chemistry · 2002

The mass of one mole of electrons is [1 electron = 9.1 × 10⁻³¹ kg, Avogadro’s number = 6.02 × 10²³]

A. 5.5 × 10⁻⁷ kg
B. 9.1 × 10⁻³¹ kg
C. 6.02 × 10⁻²³ kg
D. 1.0 × 10⁻⁷ kg
Explanation

Mass = 9.1 × 10⁻³¹ × 6.02 × 10²³ ≈ 5.5 × 10⁻⁷ kg.

34
Question 34 of 40
JAMB · Chemistry · 2002

Which gas contributes to the greenhouse effect?

A. Nitrogen
B. Oxygen
C. Carbon dioxide
D. Argon
Explanation

Carbon dioxide traps heat, contributing to the greenhouse effect.

35
Question 35 of 40
JAMB · Chemistry · 2002

The rate of a chemical reaction can be increased by

A. decreasing temperature
B. using a catalyst
C. reducing surface area
D. lowering pressure
Explanation

Catalysts lower activation energy, speeding up reactions.

36
Question 36 of 40
JAMB · Chemistry · 2002

The compound used in soap production is

A. sodium hydroxide
B. potassium chloride
C. calcium carbonate
D. magnesium sulphate
Explanation

Sodium hydroxide reacts with fats in saponification to make soap.

37
Question 37 of 40
JAMB · Chemistry · 2002

The energy change for 2H₂(g) + O₂(g) → 2H₂O(l) is the

A. activation energy
B. enthalpy change
C. free energy
D. entropy change
Explanation

The energy change in a reaction is the enthalpy change (ΔH).

38
Question 38 of 40
JAMB · Chemistry · 2002

Which substance is deliquescent?

A. Sodium chloride
B. Calcium chloride
C. Sugar
D. Silica gel
Explanation

Calcium chloride absorbs moisture, forming a solution.

39
Question 39 of 40
JAMB · Chemistry · 2002

The separation technique for purifying crude oil is

A. fractional distillation
B. filtration
C. chromatography
D. evaporation
Explanation

Crude oil is separated into fractions by fractional distillation.

40
Question 40 of 40
JAMB · Chemistry · 2002

The formula of the nitrate ion is

A. NO₂⁻
B. NO₃⁻
C. N₂O⁻
D. NH₄⁺
Explanation

The nitrate ion is NO₃⁻.

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