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POST UTME PAN-ATLANTIC UNIVERSITY 2020 Chemistry | Objective

Are you preparing for POST UTME PAN-ATLANTIC 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

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. Assume the reaction is: CaO(s) + CO2(g) → CaCO3(s).

Correct A. -1207.6 kJ/mol

B. -1208.6 kJ/mol

C. -1209.6 kJ/mol

D. -1210.6 kJ/mol

Correct Answer: A

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Question 2

A 2.5 L flask contains 0.15 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.

A. 2.1 atm

Correct B. 2.2 atm

C. 2.3 atm

D. 2.4 atm

Correct Answer: B

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Question 3

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

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 4

The diagram below shows a titration setup. Identify the part labeled A.

Correct A. Burette

B. Conical flask

C. Pipette

D. Thermometer

Correct Answer: A

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Question 5

A 2.0 g sample of a hydrocarbon is burned in a bomb calorimeter. The temperature of the calorimeter increases by 3.5°C. Calculate the heat of combustion of the hydrocarbon.

A. -3600 kJ/mol

Correct B. -3700 kJ/mol

C. -3800 kJ/mol

D. -3900 kJ/mol

Correct Answer: B

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Question 6

A 2.50 g sample of a polymer is dissolved in 25.0 mL of a solvent. If the molar mass of the polymer is 50.0 g/mol, calculate the number of moles of polymer dissolved.

Correct A. 0.0500 mol

B. 0.0505 mol

C. 0.0510 mol

D. 0.0515 mol

Correct Answer: A

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Question 7

A 0.500 L solution of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 25.0 mL of NaOH has been added.

A. 2.00

Correct B. 2.50

C. 3.00

D. 3.50

Correct Answer: B

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Question 8

A 2.00 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 1.50 g, calculate the percentage yield of the reaction.

A. 75.0%

Correct B. 80.0%

C. 85.0%

D. 90.0%

Correct Answer: B

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Question 9

A 1.00 L solution of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.

A. 50.0 mL

B. 75.0 mL

Correct C. 100 mL

D. 125 mL

Correct Answer: C

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Question 10

A 2.50 g sample of a polymer is dissolved in 25.0 mL of a solvent. If the molar mass of the polymer is 50.0 g/mol, calculate the concentration of the polymer solution.

A. 0.100 M

Correct B. 0.125 M

C. 0.150 M

D. 0.175 M

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, ΔHf(C(s)) = 0 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 sample of a non-metallic element has a mass of 2.5 g and a volume of 5.0 cm^3. If the density of the element is 3.5 g/cm^3, what is its molar mass?

A. 40.0 g/mol

B. 42.0 g/mol

Correct C. 44.0 g/mol

D. 46.0 g/mol

Correct Answer: C

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Question 13

A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. What is its molar mass?

A. 500 g/mol

Correct B. 1000 g/mol

C. 2000 g/mol

D. 5000 g/mol

Correct Answer: B

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Question 14

A solution of NaCl in water has a concentration of 0.1 M. If 10 mL of the solution is diluted to 100 mL, what is the new concentration?

Correct A. 0.01 M

B. 0.1 M

C. 1.0 M

D. 10.0 M

Correct Answer: A

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Question 15

A mixture of 2.0 g of NaCl and 1.0 g of KCl is dissolved in 100 mL of water. What is the molar concentration of the solution?

A. 0.05 M

Correct B. 0.1 M

C. 0.2 M

D. 0.5 M

Correct Answer: B

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Question 16

A polymer is a large molecule composed of many repeated subunits called monomers. Which of the following is a characteristic of polymers?

A. They are typically small molecules

B. They have a high melting point

Correct C. They are composed of many repeated subunits called monomers

D. They are typically soluble in water

Correct Answer: C

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Question 17

A solution of hydrochloric acid (HCl) is titrated with a solution of sodium hydroxide (NaOH). The reaction is as follows: HCl + NaOH → NaCl + H2O. If 25.0 mL of 1.00 M HCl is titrated with 0.500 M NaOH, what is the number of moles of NaOH required?

A. 0.0125 mol

Correct B. 0.0250 mol

C. 0.0375 mol

D. 0.0500 mol

Correct Answer: B

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Question 18

A sample of a gas occupies a volume of 2.50 L at a pressure of 1.00 atm and a temperature of 20.0°C. If the pressure is increased to 2.00 atm and the temperature is increased to 30.0°C, what is the new volume of the gas?

A. 3.75 L

B. 4.00 L

Correct C. 4.25 L

D. 4.50 L

Correct Answer: C

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Question 19

A redox reaction involves the transfer of electrons from one species to another. Which of the following is an example of a redox reaction?

Correct A. 2H2 + O2 → 2H2O

B. 2H2O → 2H2 + O2

C. 2H2 + O2 → 2H2O2

D. 2H2O2 → 2H2 + O2

Correct Answer: A

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Question 20

A solution of sodium chloride (NaCl) is electrolyzed u\sing a platinum electrode. The reaction is as follows: 2NaCl → 2Na + Cl2. If 1.00 g of NaCl is electrolyzed, what is the mass of sodium (Na) produced?

Correct A. 0.500 g

B. 0.750 g

C. 1.00 g

D. 1.25 g

Correct Answer: A

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Question 21

The reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) is a classic example of a neutralization reaction. If 25.0 mL of 0.100 M NaOH is added to 25.0 mL of 0.100 M HCl, what is the pH of the resulting solution?

A. 7.00

Correct B. 7.50

C. 8.00

D. 9.00

Correct Answer: B

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Question 22

A 2.50 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The resulting CO2 gas is collected and found to have a volume of 1.25 L at 25°C and 1 atm. What is the empirical formula of the hydrocarbon?

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 23

A solution of 0.100 M HCl is titrated with 0.100 M NaOH. If 25.0 mL of HCl is required to reach the equivalence point, what is the pH of the resulting solution?

A. 7.00

B. 7.50

Correct C. 8.00

D. 9.00

Correct Answer: C

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Question 24

A 2.50 g sample of an unknown salt is dissolved in 25.0 mL of water. The resulting solution has a conductivity of 1.25 mS/cm. What is the molar conductivity of the solution?

A. 0.050 S m^2/mol

B. 0.075 S m^2/mol

Correct C. 0.100 S m^2/mol

D. 0.125 S m^2/mol

Correct Answer: C

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Question 25

A 2.50 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The resulting CO2 gas is collected and found to have a volume of 1.25 L at 25°C and 1 atm. What is the molar mass of the hydrocarbon?

A. 50.0 g/mol

Correct B. 75.0 g/mol

C. 100 g/mol

D. 125 g/mol

Correct Answer: B

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