QCE Chemistry Practice Questions & Past Papers

Q101 · Practice questionSimple familiar1 mark

QUESTION 101

Solid iodine and iodine vapour are present in a sealed tube at constant temperature. The colour of the vapour is constant. Which statement explains this observation?

(A)

Iodine particles no longer leave the solid.

(B)

The amount of solid equals the amount of vapour.

(C)

Sublimation and deposition occur at equal, non-zero rates.

(D)

All iodine has reached the same physical state.

ABCD

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Q102 · Practice questionComplex familiar1 mark

QUESTION 102

A mixture is at equilibrium for $A (g) ⇌ 2 B (g)$ . The vessel volume is instantly halved at constant temperature. Immediately after compression, before any net reaction, the reaction quotient is

(A)

2 K_{c}

(B)

K_{c}

(C)

K_{c} / 2

(D)

4 K_{c}

ABCD

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Q103 · Practice questionComplex familiar1 mark

QUESTION 103

Two weak monoprotic acids are compared at the same temperature. Assume that their measured hydrogen ions come from acid ionisation. Which conclusion is supported by the data?

Acid	Initial concentration / mol L⁻¹	pH
X	0.100	3.00
Y	0.0100	3.20

(A)

X is stronger because its pH is lower.

(B)

Strength cannot be compared when concentrations differ.

(C)

X and Y have equal strengths because both are weak.

(D)

Y is stronger because its proportion ionised is greater.

ABCD

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Q104 · Practice questionSimple familiar1 mark

QUESTION 104

An indicator has equilibrium $H I n (a q) ⇌ H^{+} (a q) + I n^{-} (a q)$ and $p K_{a} = 6.0$ . HIn is yellow and In⁻ is blue. What is the expected dominant colour at pH 8.0?

(A)

Yellow, because HIn predominates.

(B)

Blue, because In⁻ predominates.

(C)

Green, because the two forms must have equal concentrations.

(D)

Colourless, because the indicator is completely consumed.

ABCD

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Q105 · Practice questionSimple familiar1 mark

QUESTION 105

A cell potential calculated from standard reduction potentials differs from the potential measured for the same pair of half-cells. Which observation best explains the difference?

(A)

The ion concentrations were 0.020 mol L⁻¹ rather than standard concentrations.

(B)

The voltmeter was connected to the external circuit.

(C)

The reduction half-equation was multiplied by two when balancing electrons.

(D)

A salt bridge allowed ions to migrate.

ABCD

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Q106 · Practice questionComplex familiar1 mark

QUESTION 106

The table records whether a coating forms when each metal is placed in a solution of another metal’s ions. Which metal is the strongest reducing agent?

Metal added	P²⁺ solution	Q²⁺ solution	R²⁺ solution
P	Not tested	No coating	No coating
Q	Coating	Not tested	No coating
R	Coating	Coating	Not tested

(A)

(B)

(C)

The three metals have equal reducing strengths.

(D)

ABCD

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Q107 · Practice questionComplex familiar1 mark

QUESTION 107

The reduction potentials are $E^{\circ} (A l^{3 +} / A l) = - 1.66 V$ and $E^{\circ} (A g^{+} / A g) = + 0.80 V$ . What is the standard potential for $A l (s) + 3 A g^{+} (a q) \to A l^{3 +} (a q) + 3 A g (s)$ ?

(A)

0.86 V

(B)

2.46 V

(C)

4.06 V

(D)

7.38 V

ABCD

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Q108 · Practice questionSimple familiar1 mark

QUESTION 108

What is the correct name of $F e_{2} (S O_{4})_{3}$ ?

(A)

Iron(I) sulfate

(B)

Iron(II) sulfate

(C)

Iron(III) sulfate

(D)

Iron(VI) sulfate

ABCD

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