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POST UTME UNIOSUN 2022 Chemistry | Objective

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Question 1

A sample of an ideal gas is heated from 300 K to 400 K at cons\tant volume. What is the ratio of the final pressure to the initial pressure?

Correct A. 1.33

B. 2.00

C. 3.00

D. 4.00

Correct Answer: A

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Question 2

The reaction 2NO(g) + O2(g) → 2NO2(g) is carried out in a 1.0 L flask at 298 K. If the initial pressure of NO is 0.50 atm, what is the equilibrium pressure of NO2?

A. 0.25 atm

B. 0.50 atm

Correct C. 1.00 atm

D. 2.00 atm

Correct Answer: C

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Question 3

A 2.0 g sample of an unknown hydrocarbon is burned in a bomb calorimeter. If the heat of combustion is -3500 J/g, what is the molar mass of the hydrocarbon?

A. 50 g/mol

Correct B. 100 g/mol

C. 150 g/mol

D. 200 g/mol

Correct Answer: B

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Question 4

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

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 5

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

Correct A. To measure the volume of the titrant

B. To measure the volume of the analyte

C. To mix the titrant and analyte

D. To measure the pH of the solution

Correct Answer: A

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Question 6

The reaction of cyclohexane with bromine in the presence of light produces a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?

A. 1,2-dibromocyclohexane

Correct B. 1,4-dibromocyclohexane

C. cis-1,2-dibromocyclohexane

D. trans-1,4-dibromocyclohexane

Correct Answer: B

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Question 7

A 0.500 M solution of NaCl is electrolyzed u\sing a platinum electrode. The cell potential is 2.71 V. What is the mass of Cl2 produced at the anode after 2.00 hours?

Correct A. 0.250 g

B. 0.500 g

C. 1.00 g

D. 2.00 g

Correct Answer: A

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Question 8

The atomic radius of an element is 100 pm. What is the expected atomic radius of the element's isotope with a mass number of 200?

A. 50 pm

B. 100 pm

Correct C. 150 pm

D. 200 pm

Correct Answer: C

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Question 9

A 1.00 M solution of H2SO4 is titrated with 0.500 M NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 10

A 0.500 M solution of NH3 is electrolyzed u\sing a platinum electrode. The cell potential is 1.33 V. What is the mass of N2 produced at the anode after 1.00 hour?

A. 0.100 g

B. 0.200 g

Correct C. 0.500 g

D. 1.00 g

Correct Answer: C

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Question 11

In a titration experiment, 25.0 mL of 0.100 M HCl is added to 50.0 mL of 0.0500 M NaOH. What is the pH of the resulting solution?

A. ( 7.00 )

Correct B. ( 9.00 )

C. ( 10.0 )

D. ( 12.0 )

Correct Answer: B

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Question 12

The rate cons\tant for the decomposition of N2O5 is 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the half-life of the reaction?

Correct A. \( 2.80 \times 10^3 \) s

B. \( 2.80 \times 10^2 \) s

C. \( 2.80 \times 10^1 \) s

D. \( 2.80 \times 10^\( -1 \ \) ) s

Correct Answer: A

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Question 13

A solution contains 0.100 M NaOH and 0.0500 M HCl. What is the pH of the resulting solution?

Correct A. ( 7.00 )

B. ( 9.00 )

C. ( 10.0 )

D. ( 12.0 )

Correct Answer: A

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Question 14

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO(g)?

Correct A. \( -110.5 \) kJ/mol

B. \( -110.5 \) kJ/mol

C. \( -110.5 \) kJ/mol

D. \( -110.5 \) kJ/mol

Correct Answer: A

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Question 15

The rate cons\tant for the reaction 2NO(g) → N2O2(g) is 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the half-life of the reaction?

Correct A. \( 2.80 \times 10^3 \) s

B. \( 2.80 \times 10^2 \) s

C. \( 2.80 \times 10^1 \) s

D. \( 2.80 \times 10^\( -1 \ \) ) s

Correct Answer: A

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Question 16

The s\tandard electrode potential of the couple Zn2+/Zn is -0.76 V. What is the s\tandard electrode potential of the couple Cu2+/Cu if the cell reaction is Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)?

Correct A. -0.34 V

B. -0.76 V

C. 0.42 V

D. 1.18 V

Correct Answer: A

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Question 17

A 2.5 L flask contains 0.5 mol of an ideal gas at 25°C. What is the pressure of the gas in the flask?

Correct A. 1.01 × 10^5 Pa

B. 2.02 × 10^5 Pa

C. 3.03 × 10^5 Pa

D. 4.04 × 10^5 Pa

Correct Answer: A

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Question 18

The half-reaction for the reduction of MnO4- is MnO4- + 8H+ + 5e- → Mn2+ + 4H2O. What is the s\tandard electrode potential of the couple MnO4-/Mn2+?

Correct A. 1.51 V

B. 1.51 V

C. 1.51 V

D. 1.51 V

Correct Answer: A

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Question 19

A 2.0 L flask contains 0.5 mol of an ideal gas at 25°C. What is the pressure of the gas in the flask?

Correct A. 1.01 × 10^5 Pa

B. 2.02 × 10^5 Pa

C. 3.03 × 10^5 Pa

D. 4.04 × 10^5 Pa

Correct Answer: A

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Question 20

The half-reaction for the reduction of NO3- is NO3- + 4H+ + 3e- → NO + 2H2O. What is the s\tandard electrode potential of the couple NO3-/NO?

Correct A. 0.87 V

B. 0.87 V

C. 0.87 V

D. 0.87 V

Correct Answer: A

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Question 21

Determine the oxidation state of nitrogen in the compound NO2.

A. +1

B. +2

Correct C. +3

D. +4

Correct Answer: C

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Question 22

What is the major product of the reaction between 2-methylpropene and HCl?

Correct A. 2-chloro-2-methylpropane

B. 2-chloro-2-methylbu\tane

C. 2-chloro-3-methylbu\tane

D. 2-chloro-2-methylpen\tane

Correct Answer: A

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Question 23

Solve for x in the equation: \( \log_{10} \( x^2 \ \) = 4 ).

A. 2

B. 4

C. 8

Correct D. 16

Correct Answer: D

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Question 24

What is the s\tandard enthalpy of formation of CO2(g)?

Correct A. -393.5 kJ/mol

B. +393.5 kJ/mol

C. -393.5 kJ/mol

D. +393.5 kJ/mol

Correct Answer: A

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Question 25

A 2.50-g sample of a metal oxide is heated in a crucible until it is completely reduced to its constituent elements. If the mass of the metal obtained is 1.75 g, what is the mass of oxygen in the original sample?

Correct A. 0.75 g

B. 1.00 g

C. 1.25 g

D. 1.50 g

Correct Answer: A

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