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POST UTME UNILAG 2017 Chemistry | Objective

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Question 1

At 273 K, the volume of 1 mole of an ideal gas is 22.4 L. If the temperature is increased to 373 K, what is the new volume of the gas?

Correct A. 44.8 L

B. 22.4 L

C. 11.2 L

D. 5.6 L

Correct Answer: A

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Question 2

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. The mass of the metal oxide produced is 1.8 g. What is the percentage yield of the reaction?

Correct A. 72%

B. 80%

C. 88%

D. 96%

Correct Answer: A

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Question 3

A solution contains 5.0 g of NaCl per 100 mL of water. What is the molarity of the solution?

A. 0.1 M

Correct B. 0.5 M

C. 1.0 M

D. 5.0 M

Correct Answer: B

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Question 4

A 2.0 L flask contains 1.0 mol of an ideal gas at 298 K. What is the pressure of the gas?

Correct A. 101.3 kPa

B. 202.6 kPa

C. 303.9 kPa

D. 405.2 kPa

Correct Answer: A

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Question 5

A 10.0 g sample of a metal is heated in air to produce a metal oxide. The mass of the metal oxide produced is 12.0 g. What is the percentage yield of the reaction?

A. 80%

Correct B. 90%

C. 92%

D. 96%

Correct Answer: B

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Question 6

The rate cons\tant of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.2 M, what is the concentration after 10 minutes?

A. 0.01 M

Correct B. 0.02 M

C. 0.03 M

D. 0.04 M

Correct Answer: B

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Question 7

A 2.5 g sample of a polymer is dissolved in 50 mL of a solvent. If the density of the solution is 1.2 g/mL, what is the molarity of the solution?

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 8

A redox reaction involves the transfer of 2 electrons. If the s\tandard reduction potential of the oxidizing agent is +0.5 V, what is the s\tandard reduction potential of the reducing agent?

A. -0.5 V

B. -0.6 V

C. -0.7 V

Correct D. -0.8 V

Correct Answer: D

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Question 9

A solution containing 0.1 M NaCl is electrolyzed u\sing a platinum electrode. If the current is 2 A, what is the mass of Cl2 produced after 10 minutes?

A. 0.1 g

B. 0.2 g

Correct C. 0.3 g

D. 0.4 g

Correct Answer: C

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Question 10

A 1.0 M solution of H2SO4 is mixed with 1.0 M solution of NaOH. What is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.1 g, calculate the percentage yield of the metal oxide.

Correct A. 65%

B. 70%

C. 75%

D. 80%

Correct Answer: A

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Question 12

The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of methane (CH4) at 298 K.

Correct A. -891 kJ/mol

B. -891.5 kJ/mol

C. -892 kJ/mol

D. -892.5 kJ/mol

Correct Answer: A

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Question 13

A solution of 0.1 M NaOH is mixed with a solution of 0.1 M HCl. What is the pH of the resulting solution?

A. 7

Correct B. 7.5

C. 8

D. 8.5

Correct Answer: B

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Question 14

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.1 g, calculate the percentage yield of the metal oxide.

Correct A. 65%

B. 70%

C. 75%

D. 80%

Correct Answer: A

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Question 15

The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of methane (CH4) at 298 K.

Correct A. -891 kJ/mol

B. -891.5 kJ/mol

C. -892 kJ/mol

D. -892.5 kJ/mol

Correct Answer: A

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Question 16

The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). What is the oxidation state of copper in CuSO4?

Correct A. +2

B. -2

C. 0

D. +1

Correct Answer: A

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Question 17

A sample of benzene (C6H6) has a mass of 12.0 g. Calculate the number of moles of benzene present in the sample.

Correct A. 0.154 mol

B. 0.1545 mol

C. 0.1541 mol

D. 0.1549 mol

Correct Answer: A

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Question 18

A 2.50 L flask contains 0.500 mol of an ideal gas at 27°C. What is the pressure of the gas?

Correct A. 1.01 × 10^5 Pa

B. 1.02 × 10^5 Pa

C. 1.03 × 10^5 Pa

D. 1.04 × 10^5 Pa

Correct Answer: A

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Question 19

The diagram below shows a titration setup. What is the purpose of the burette?

Correct A. To measure the volume of the solution

B. To measure the volume of the solid

C. To measure the volume of the gas

D. To measure the volume of the liquid

Correct Answer: A

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Question 20

The reaction between sodium hydroxide and hydrochloric acid is represented by the equation: NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l). What is the type of reaction?

A. Synthesis reaction

B. Decomposition reaction

C. Single displacement reaction

Correct D. Double displacement reaction

Correct Answer: D

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Question 21

The atomic radius of an element in the periodic table increases down a group and decreases across a period. What is the reason for this tr\end?

Correct A. The atomic radius increases down a group due to the addition of new energy levels, while it decreases across a period due to the increase in effective nuclear charge.

B. The atomic radius decreases down a group due to the increase in effective nuclear charge, while it increases across a period due to the addition of new energy levels.

C. The atomic radius remains cons\tant down a group and across a period due to the equal number of protons and electrons.

D. The atomic radius increases down a group and across a period due to the increase in the number of protons.

Correct Answer: A

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Question 22

A redox reaction involves the transfer of electrons from one species to another. What is the driving force behind this transfer?

A. The driving force behind the transfer of electrons is the difference in electronegativity between the two species.

B. The driving force behind the transfer of electrons is the difference in oxidation states between the two species.

Correct C. The driving force behind the transfer of electrons is the difference in reduction potentials between the two species.

D. The driving force behind the transfer of electrons is the difference in atomic radii between the two species.

Correct Answer: C

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Question 23

A solution of 0.1 M HCl is titrated with a solution of 0.1 M NaOH. What is the pH of the solution after the reaction is complete?

Correct A. 7

B. 8

C. 9

D. 10

Correct Answer: A

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Question 24

A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?

Correct A. To measure the volume of the solution being added.

B. To measure the volume of the solution being titrated.

C. To mix the solutions together.

D. To separate the solutions.

Correct Answer: A

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Question 25

A diagram of a redox reaction is shown below. What is the role of the catalyst in this reaction?

Correct A. To speed up the reaction.

B. To slow down the reaction.

C. To change the direction of the reaction.

D. To change the products of the reaction.

Correct Answer: A

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