JAMB Chemistry Past Questions 2024

10 questions from the JAMB 2024 Chemistry paper, with answers and explanations. Tap "Show answer" under each one when you are ready.

JAMB 2024Question 1 · Acids, Bases, and Salts

The pH of a

0.001 mol d m^{- 3}

of H

_{2}

_{4}

is [Log

_{10}

2 = 0.3]

A.2.7
B.3.0
C.3.3
D.2.0

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Answer: A. 2.7

$H_{2} S O_{4}$ is diprotic: [ $H^{+}$ ] = 2x0.001 = $2 \times 1 0^{- 3}$ . pH = -log( $2 \times 1 0^{- 3}$ ) = 3-log(2) = 3-0.3 = 2.7.

JAMB 2024Question 2 · Atomic Structure and Chemical Bonding

The shape of the molecule of Carbon(IV) oxide is

A.tetrahedral
B.pyramidal
C.plannar
D.linear

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Answer: D. linear

Carbon(IV) oxide $(C O_{2})$ has a linear molecular shape.

JAMB 2024Question 3 · Chemistry of Metals

Rust on the surface of a metal sheet contains

A.hydrated iron(II)oxide
B.hydrated iron(III)oxide
C.iron(III)hydroxide
D.iron(III) trioxocarbonate(IV)

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Answer: B. hydrated iron(III)oxide

Rust is hydrated iron(III) oxide.

JAMB 2024Question 4 · Chemistry of Non-metals and Gases

The reaction of hydrogen and chlorine to produce hydrogen chloride gas is explosive in

A.diffused light
B.sunlight
C.infrared light
D.Raman light

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Answer: B. sunlight

The reaction between hydrogen and chlorine gas is explosive in direct sunlight, which triggers a rapid photochemical chain reaction.

JAMB 2024Question 5 · Electrochemistry and Redox Reactions

The amount of Faraday required to discharge 4.5 moles of Al

^{3 +}

A.13.5
B.4.5
C.7.5
D.1.5

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Answer: A. 13.5

$A l^{3 +}$ + 3e- → Al requires 3 Faradays per mole of Al; for $4.5 mol$ $A l^{3 +}$ , 3x4.5 = 13.5 Faradays are needed.

JAMB 2024Question 6 · Environmental and Industrial Chemistry

_{7}^{14}

N + X →

_{6}^{14}

C +

_{1}^{1}

P In the reaction above, X is

A.a proton
B.an alpha particle
C.a beta particle
D.a neutron

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Answer: D. a neutron

Balancing N-14 + X → C-14 + H-1(proton): mass balance gives X mass=1, charge balance gives X charge=0, so X is a neutron.

JAMB 2024Question 7 · Organic Chemistry

When a few drops of Millon reagents is added to egg-white solution in a test tube, the white precipitate changes to

A.orange
B.brick red
C.reddish brown
D.blue

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Answer: B. brick red

Millon's reagent added to a protein (egg white) solution and heated produces a brick-red colouration, a positive test for tyrosine-containing proteins.

JAMB 2024Question 8 · Organic Chemistry

Benzene formed nitrobenzene at temperature of 60

^{0}

C when it reacts with mixture of concentrated trioxonitrate(V) acid and concentrated

A.phosphoric acid
B.hydrochloric acid
C.tetraoxosulphate(VI) acid
D.hydrogen iodide

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Answer: C. tetraoxosulphate(VI) acid

Benzene reacts with a mixture of concentrated trioxonitrate(V) acid and concentrated tetraoxosulphate(VI) acid (the latter as catalyst/dehydrating agent) to form nitrobenzene.

JAMB 2024Question 9 · Physical Chemistry

For chemical reaction to be spontaneous, ∆G must be

A.positive
B.negative
C.zero
D.equal to the enthalpy change

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Answer: B. negative

A reaction is spontaneous when its Gibbs free energy change (ΔG) is negative.

JAMB 2024Question 10 · Quantitative Chemistry

The number of molecules of helium gas contained in

11.5 g

of the gas is

A. $1.73 \times 1 0^{23}$
B. $1.73 \times 1 0^{22}$
C. $1.73 \times 1 0^{24}$
D. $1.73 \times 1 0^{21}$

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Answer: C. $1.73 \times 1 0^{24}$

The amount is $11.5/4 = 2.875 mol$ . Therefore the number of molecules is $(2.875) (6.02 \times 1 0^{23}) \approx 1.73 \times 1 0^{24}$ .

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JAMB Chemistry Past Questions 2024

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