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POST UTME BOWEN UNIVERSITY 2020 Chemistry | Objective

Are you preparing for POST UTME BOWEN UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

A 2.5 g sample of a hydrocarbon is burned in a combustion calorimeter. If the volume of carbon dioxide gas produced is 2.2 L at 25°C and 1 atm, calculate the molar mass of the hydrocarbon.

A. 120 g/mol

B. 150 g/mol

Correct C. 180 g/mol

D. 200 g/mol

Correct Answer: C

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Question 2

A solution of sodium chloride is prepared by dissolving 35.5 g of NaCl in 250 mL of water. Calculate the molarity of the solution.

A. 0.15 M

Correct B. 0.20 M

C. 0.25 M

D. 0.30 M

Correct Answer: B

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Question 3

A mixture of 25.0 g of ethanol (C2H5OH) and 15.0 g of propanol (C3H7OH) is heated to produce a gas. If the total volume of the gas produced is 2.5 L at 25°C and 1 atm, calculate the percentage of ethanol in the mixture.

A. 60%

Correct B. 65%

C. 70%

D. 75%

Correct Answer: B

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Question 4

A 5.0 L flask contains 0.50 M NaCl solution. If 10.0 mL of 2.0 M HCl is added to the solution, calculate the new concentration of the solution.

A. 0.55 M

B. 0.60 M

Correct C. 0.65 M

D. 0.70 M

Correct Answer: C

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Question 5

A 2.0 L flask contains 0.20 M NaOH solution. If 5.0 mL of 1.0 M HCl is added to the solution, calculate the new concentration of the solution.

A. 0.22 M

Correct B. 0.25 M

C. 0.28 M

D. 0.30 M

Correct Answer: B

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Question 6

Determine the pH of a 0.1 M solution of HCl after 10 mL of 1 M NaOH has been added to 20 mL of the HCl solution. Assume the volume of the solution remains cons\tant.

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 7

A sample of water contains 10 ppm of dissolved oxygen. If 100 mL of this water is taken, what is the mass of oxygen present in the sample?

Correct A. 0.01 g

B. 0.1 g

C. 1 g

D. 10 g

Correct Answer: A

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Question 8

A polymer has a molecular weight of 50000 g/mol. If 1 g of this polymer is dissolved in 100 mL of water, what is the concentration of the solution in g/L?

Correct A. 0.05 g/L

B. 0.5 g/L

C. 5 g/L

D. 50 g/L

Correct Answer: A

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Question 9

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the volume of HCl required to reach the equivalence point?

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 10

A sample of soil contains 10% clay, 20% silt, and 70% sand. If 100 g of this soil is taken, what is the mass of clay present in the sample?

Correct A. 10 g

B. 20 g

C. 30 g

D. 40 g

Correct Answer: A

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Question 11

A polymer is formed by the condensation reaction between a diol and a diacid. If the molecular weight of the diol is 180 g/mol and the molecular weight of the diacid is 150 g/mol, what is the molecular weight of the polymer formed?

A. 450

B. 600

Correct C. 900

D. 1200

Correct Answer: C

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Question 12

A solution of 10 g of NaCl in 100 g of water has a boiling point elevation of 0.5°C. What is the molality of the solution?

A. 0.1 m

Correct B. 0.2 m

C. 0.3 m

D. 0.4 m

Correct Answer: B

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Question 13

A sample of air contains 20% oxygen, 70% nitrogen, and 10% carbon dioxide by volume. What is the partial pressure of oxygen in a sample of air at 1 atm total pressure?

Correct A. 0.2 atm

B. 0.4 atm

C. 0.6 atm

D. 0.8 atm

Correct Answer: A

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Question 14

A 1.0 M solution of HCl is titrated with a 1.0 M solution of NaOH. What is the pH of the solution after 25 mL of NaOH has been added?

A. 1

B. 2

Correct C. 3

D. 4

Correct Answer: C

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Question 15

A 100 mL sample of a solution containing 0.1 M NaOH is titrated with a 1.0 M solution of HCl. What is the volume of HCl required to reach the equivalence point?

A. 50 mL

Correct B. 100 mL

C. 150 mL

D. 200 mL

Correct Answer: B

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Question 16

The rate cons\tant of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?

A. 0.05 M

Correct B. 0.025 M

C. 0.1 M

D. 0.5 M

Correct Answer: B

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Question 17

A 2.5 g sample of a metal is dissolved in 50 mL of 1 M HCl. If the metal is 95% pure, what is the molar mass of the metal?

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 18

The reaction between H2 and I2 is catalyzed by Pt. If 1.5 g of H2 reacts with 1.2 g of I2, what is the limiting reac\tant?

Correct A. H2

B. I2

C. Pt

D. Neither

Correct Answer: A

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Question 19

The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. If 2.5 mol of CO2 is produced at 298 K, what is the total enthalpy change?

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 20

A 2.5 M solution of NaOH is mixed with a 1.5 M solution of HCl. If 50 mL of the NaOH solution is added to 100 mL of the HCl solution, 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 21

The atomic number of an element is 12. If the element has 3 electrons in its outermost shell, what is the expected oxidation state of the element in a compound?

A. 2

Correct B. 3

C. 4

D. 5

Correct Answer: B

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Question 22

A polymer has a molecular weight of 50000 g/mol. If 2.5 g of the polymer is dissolved in 100 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 g/L

D. 2 g/L

Correct Answer: B

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Question 23

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. If 2.5 mol of CO2 is formed at 298 K, what is the total enthalpy change for the reaction?

Correct A. -987.5 kJ

B. -993.5 kJ

C. -998.5 kJ

D. -1002.5 kJ

Correct Answer: A

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Question 24

The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is initially present, what is the mass of the subs\tance remaining after 10 years?

A. 25 g

Correct B. 50 g

C. 75 g

D. 100 g

Correct Answer: B

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Question 25

A solution contains 2 M HCl and 1 M NaOH. If 10 mL of the solution is titrated with 1 M 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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