POST UTME UNN 2020 Chemistry | Objective

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Question 1 View Details
A mixture of 0.5 mol of CO2 and 0.3 mol of O2 is placed in a 2.0 L container at 25°C. Calculate the partial pressure of CO2 in the mixture.
A. 0.5 atm
Correct B. 0.7 atm
C. 1.0 atm
D. 1.5 atm

Correct Answer: B

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Question 2 View Details
A sample of a polymer has a molecular weight of 50,000 g/mol. If 0.5 g of the polymer is dissolved in 20 mL of solvent, what is the concentration of the solution in g/L?
A. 0.25 g/L
Correct B. 0.5 g/L
C. 1.0 g/L
D. 2.0 g/L

Correct Answer: B

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Question 3 View Details
The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO?
Correct A. -110.5 kJ/mol
B. -137.3 kJ/mol
C. -393.5 kJ/mol
D. -745.3 kJ/mol

Correct Answer: A

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Question 4 View Details
A solution contains 0.1 M NaCl and 0.2 M NaOH. What is the pH of the solution?
A. 1.0
B. 2.0
C. 3.0
Correct D. 4.0

Correct Answer: D

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Question 5 View Details
A 2.0 L container is filled with 1.0 mol of H2 and 1.0 mol of O2 at 25°C. What is the partial pressure of H2 in the mixture?
A. 0.5 atm
B. 0.7 atm
Correct C. 1.0 atm
D. 1.5 atm

Correct Answer: C

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Question 6 View Details
A 0.5 M solution of NaOH is prepared by dissolving 25 g of NaOH in 1 L of water. Calculate the number of moles of NaOH used in preparing the solution.
A. 0.5 mol
Correct B. 0.25 mol
C. 0.75 mol
D. 1.0 mol

Correct Answer: B

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Question 7 View Details
The half-life of a radioactive subs\tance is 5 years. If the initial amount of the subs\tance is 100 g, how much of the subs\tance will remain after 10 years?
Correct A. 25 g
B. 50 g
C. 75 g
D. 100 g

Correct Answer: A

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Question 8 View Details
A 2.0 L sample of a gas at 27°C and 1.0 atm is collected over water at 27°C. If the vapor pressure of water at 27°C is 0.031 atm, what is the partial pressure of the gas?
Correct A. 0.969 atm
B. 0.969 kPa
C. 1.0 atm
D. 1.0 kPa

Correct Answer: A

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Question 9 View Details
A 10.0 g sample of a compound containing only carbon and hydrogen is analyzed and found to contain 6.0 g of carbon and 4.0 g of hydrogen. What is the empirical formula of the compound?
Correct A. CH
B. C2H
C. C3H2
D. C4H3

Correct Answer: A

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Question 10 View Details
A 5.0 L sample of a gas at 25°C and 2.0 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 0.031 atm, what is the partial pressure of the gas?
Correct A. 1.969 atm
B. 1.969 kPa
C. 2.0 atm
D. 2.0 kPa

Correct Answer: A

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Question 11 View Details
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. -110.5 kJ/mol
B. -110.5 kJ/mol
C. -110.5 kJ/mol
Correct D. -110.5 kJ/mol

Correct Answer: D

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Question 12 View Details
A 2.5 M solution of HCl is titrated with 0.5 M NaOH. Calculate the pH of the solution after 25 mL of NaOH has been added.
A. 2.5
B. 2.5
C. 2.5
Correct D. 2.5

Correct Answer: D

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Question 13 View Details
The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of formation of N2(g) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol.
A. 0 kJ/mol
B. 0 kJ/mol
C. 0 kJ/mol
Correct D. 0 kJ/mol

Correct Answer: D

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Question 14 View Details
A 1.0 M solution of H2SO4 is titrated with 0.5 M NaOH. Calculate the pH of the solution after 50 mL of NaOH has been added.
A. 1.0
B. 1.0
C. 1.0
Correct D. 1.0

Correct Answer: D

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Question 15 View Details
The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of formation of C(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. 0 kJ/mol
B. 0 kJ/mol
C. 0 kJ/mol
Correct D. 0 kJ/mol

Correct Answer: D

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Question 16 View Details
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 17 View Details
The polymerization of styrene produces a polymer with the following structure: [-CH2-CH(C6H5)-]n. What is the type of polymerization reaction that occurred?
Correct A. Addition polymerization
B. Condensation polymerization
C. Ring-opening polymerization
D. Step-growth polymerization

Correct Answer: A

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Question 18 View Details
The following diagram shows a titration setup. 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 19 View Details
The following diagram shows a circuit. What is the purpose of the resistor?
Correct A. To reduce the current flowing through the circuit
B. To increase the voltage across the circuit
C. To measure the voltage across the circuit
D. To measure the current flowing through the circuit

Correct Answer: A

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Question 20 View Details
The following diagram shows a graph. What is the type of relationship between the variables?
A. Direct variation
Correct B. Inverse variation
C. Proportional variation
D. Inverse square variation

Correct Answer: B

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Question 21 View Details
A 0.1 M solution of NaOH is titrated with 0.1 M HCl. If 20 mL of HCl is required to reach the equivalence point, what is the pH of the resulting solution?
A. 7
B. 9
C. 10
Correct D. 12

Correct Answer: D

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Question 22 View Details
A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. What is the molar mass of the repeating unit?
A. 200 g/mol
B. 400 g/mol
Correct C. 500 g/mol
D. 1000 g/mol

Correct Answer: C

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Question 23 View Details
A solution of 0.1 M HCl is mixed with a solution of 0.1 M NaOH. If the initial pH of the HCl solution is 1, what is the pH of the resulting solution after the reaction is complete?
A. 7
Correct B. 9
C. 10
D. 12

Correct Answer: B

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Question 24 View Details
A 1 M solution of H2SO4 is titrated with 1 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the pH of the resulting solution?
A. 7
B. 9
Correct C. 10
D. 12

Correct Answer: C

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Question 25 View Details
A 0.1 M solution of NaOH is titrated with 0.1 M HCl. If 20 mL of HCl is required to reach the equivalence point, what is the concentration of the resulting solution?
A. 0.05 M
Correct B. 0.1 M
C. 0.15 M
D. 0.2 M

Correct Answer: B

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