Practice Post UTME UNIPORT chemistry 2022 Past Questions

Question 1

Determine the s\tandard electrode potential of the cell represented by the following reaction: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O. Given that the s\tandard electrode potential of the MnO4-/Mn2+ couple is +1.23 V.

A. +1.23 V

Correct B. +1.53 V

C. +1.73 V

D. +1.93 V

Correct Answer: B

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Question 2

A diagram of a titration setup is shown below. If the burette contains 0.1 M HCl and the initial volume is 20 mL, what is the concentration of the NaOH solution if 25 mL of it is required to reach the equivalence point?

A. 0.05 M

B. 0.1 M

Correct C. 0.15 M

D. 0.2 M

Correct Answer: C

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Question 3

The diagram below represents a simple electric circuit. If the resis\tance of the circuit is 10 Ω and the voltage source is 12 V, what is the current flowing through the circuit?

A. 0.6 A

Correct B. 1.2 A

C. 1.8 A

D. 2.4 A

Correct Answer: B

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Question 4

A sample of a metal (M) reacts with hydrochloric acid (HCl) to produce hydrogen gas. The reaction is represented by the equation: M + 2HCl → MCl2 + H2. If 2.5 g of the metal is reacted with 20 mL of 1 M HCl, what is the volume of hydrogen gas produced at STP?

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 5

A diagram of a simple distillation apparatus is shown below. If the boiling point of the liquid is 100°C and the temperature of the condenser is 20°C, what is the temperature of the vapor leaving the condenser?

A. 40°C

Correct B. 60°C

C. 80°C

D. 100°C

Correct Answer: B

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Question 6

A 2.5 L sample of a gas at 27°C and 1 atm is compressed to 1 L at 127°C. Calculate the work done on the gas, assuming it behaves as an ideal gas.

A. -2.5 kJ

Correct B. -5.0 kJ

C. -7.5 kJ

D. -10.0 kJ

Correct Answer: B

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Question 7

A solution containing 0.1 M CuSO4 is mixed with a solution containing 0.1 M Na2S. Calculate the number of moles of CuS formed.

A. 0.005 mol

Correct B. 0.01 mol

C. 0.015 mol

D. 0.02 mol

Correct Answer: B

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Question 8

A 10 g sample of a metal $ atomic mass = 50 g/mol $ is heated to 1000°C. Calculate the energy required to raise the temperature of the metal by 100°C.

A. 100 J

Correct B. 200 J

C. 300 J

D. 400 J

Correct Answer: B

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Question 9

A 2.5 L sample of a gas at 27°C and 1 atm is compressed to 1 L at 127°C. Calculate the work done on the gas, assuming it behaves as an ideal gas.

A. -2.5 kJ

Correct B. -5.0 kJ

C. -7.5 kJ

D. -10.0 kJ

Correct Answer: B

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Question 10

A solution containing 0.1 M CuSO4 is mixed with a solution containing 0.1 M Na2S. Calculate the number of moles of CuS formed.

A. 0.005 mol

Correct B. 0.01 mol

C. 0.015 mol

D. 0.02 mol

Correct Answer: B

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Question 11

Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol.

Correct A. -1785.6 kJ/mol

B. -1785.9 kJ/mol

C. -1786.1 kJ/mol

D. -1786.3 kJ/mol

Correct Answer: A

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Question 12

A 2.5 M solution of H2SO4 is electrolyzed u\sing a platinum electrode. Calculate the mass of oxygen gas collected at the anode after 2 hours, given that the current is 5 A and the cell potential is 2.0 V.

A. 0.15 g

B. 0.20 g

Correct C. 0.25 g

D. 0.30 g

Correct Answer: C

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Question 13

A sample of air contains 20% O2 and 80% N2 by volume. Calculate the partial pressure of O2 in the air at 25°C and 1 atm.

A. 0.20 atm

Correct B. 0.25 atm

C. 0.30 atm

D. 0.35 atm

Correct Answer: B

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Question 14

A 10% solution of NaCl is prepared by dissolving 10 g of NaCl in 90 g of water. Calculate the molality of the solution.

A. 0.10 m

B. 0.15 m

Correct C. 0.20 m

D. 0.25 m

Correct Answer: C

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Question 15

A 2.0 M solution of HCl is electrolyzed u\sing a platinum electrode. Calculate the mass of chlorine gas collected at the anode after 1 hour, given that the current is 3 A and the cell potential is 1.5 V.

A. 0.10 g

B. 0.15 g

Correct C. 0.20 g

D. 0.25 g

Correct Answer: C

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Question 16

The rate cons\tant (k) of a first-order reaction is related to the half-life $ t_\( 1/2 \ $) by the equation: $ k = \frac{ln 2}{t_{1/2}} $. If the half-life of a reaction is 10 minutes, what is the rate cons\tant (k) in min^$ -1 $?

Correct A. 0.0693 min^$ -1 $

B. 0.693 min^$ -1 $

C. 6.93 min^$ -1 $

D. 69.3 min^$ -1 $

Correct Answer: A

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Question 17

The s\tandard enthalpy of formation $ ΔH_\( f \ $) of CO_(2) is -393.5 kJ/mol. If 2.5 mol of CO_(2) is produced at 298 K, what is the total enthalpy change (ΔH) in kJ?

Correct A. -987.5 kJ

B. -987.75 kJ

C. -987.5 kJ/mol

D. -987.75 kJ/mol

Correct Answer: A

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Question 18

The equilibrium cons\tant $ K_\( c \ $) for the reaction: $ N_2O_4 \rightleftharpoons 2NO_2 $ is 1.8 × 10^$ -3 $ at 298 K. If the initial concentration of N_(2)O_(4) is 0.1 M, what is the concentration of NO_(2) at equilibrium?

Correct A. 0.0015 M

B. 0.015 M

C. 0.15 M

D. 1.5 M

Correct Answer: A

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Question 19

The atomic radius of an element is 100 pm. If the element has an electron configuration of [Ar] 4s^(2) 3d^(5), what is the expected oxidation state of the element?

Correct A. +2

B. +3

C. +5

D. +7

Correct Answer: A

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Question 20

The solubility product cons\tant $ K_\( sp \ $) of AgCl is 1.8 × 10^$ -10 $ at 298 K. If the concentration of Ag^$ + $ is 0.01 M, what is the concentration of Cl^$ - $ at equilibrium?

A. 1.8 × 10^$ -9 $ M

Correct B. 1.8 × 10^$ -10 $ M

C. 1.8 × 10^$ -11 $ M

D. 1.8 × 10^$ -12 $ M

Correct Answer: B

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Question 21

The s\tandard enthalpy of formation $ ΔH_\( f \ $) of H_(2)O is -285.8 kJ/mol. If 2.5 mol of H_(2)O is produced at 298 K, what is the total enthalpy change (ΔH) in kJ?

Correct A. -716.5 kJ

B. -716.75 kJ

C. -716.5 kJ/mol

D. -716.75 kJ/mol

Correct Answer: A

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Question 22

The equilibrium cons\tant $ K_\( c \ $) for the reaction: $ N_2O_4 \rightleftharpoons 2NO_2 $ is 1.8 × 10^$ -3 $ at 298 K. If the initial concentration of N_(2)O_(4) is 0.1 M, what is the concentration of NO_(2) at equilibrium?

Correct A. 0.0015 M

B. 0.015 M

C. 0.15 M

D. 1.5 M

Correct Answer: A

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Question 23

The atomic radius of an element is 100 pm. If the element has an electron configuration of [Ar] 4s^(2) 3d^(5), what is the expected oxidation state of the element?

Correct A. +2

B. +3

C. +5

D. +7

Correct Answer: A

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Question 24

A solution of $CuSO_4$ is electrolyzed u\sing a platinum electrode. The anode reaction is $2H_2O(l) \rightarrow O_2(g) + 4H^+(aq) + 4e^-$.

A. The anode potential is more negative than the cathode potential.

B. The anode potential is more positive than the cathode potential.

C. The anode reaction is a reduction reaction.

Correct D. The anode reaction is an oxidation reaction.

Correct Answer: D

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Question 25

A 0.1 M solution of $NaOH$ is mixed with a 0.1 M solution of $HCl$. The resulting solution is then electrolyzed u\sing a platinum electrode.

A. The resulting solution will be a strong base.

B. The resulting solution will be a weak base.

Correct C. The resulting solution will be a strong acid.

D. The resulting solution will be a weak acid.

Correct Answer: C

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