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POST UTME OAU 2022 Chemistry | Objective

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Question 1

A 0.1 M solution of NaOH is prepared by dissolving 4 g of NaOH in water to make 1 L of solution. What is the pH of the solution?

A. 13

B. 12

C. 11

Correct D. 10

Correct Answer: D

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Question 2

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 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 3

A 1 L solution of 0.1 M HCl is prepared by dissolving 3.5 g of HCl in water. What is the pH of the solution?

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 4

A diagram of a gas law setup is shown below. What is the purpose of the manometer in this setup?

Correct A. To measure the pressure of the gas

B. To measure the volume of the gas

C. To measure the temperature of the gas

D. To measure the density of the gas

Correct Answer: A

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Question 5

A 1 L solution of 0.1 M NaOH is prepared by dissolving 4 g of NaOH in water. What is the concentration of the solution in terms of molarity?

Correct A. 0.1 M

B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: A

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Question 6

Determine the number of moles of electrons transferred during the electrolysis of 2.5 L of water at 25°C and 1 atm, given that the cell potential is 1.23 V and the current is 0.5 A.

A. 0.5 mol

Correct B. 1.0 mol

C. 1.5 mol

D. 2.0 mol

Correct Answer: B

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Question 7

A polymer is prepared by the condensation reaction of a diol with a diacid. The molecular weight of the polymer is 50,000 g/mol. If the molecular weight of the repeating unit is 200 g/mol, what is the degree of polymerization?

A. 200

Correct B. 250

C. 300

D. 350

Correct Answer: B

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Question 8

A sample of nitrogen gas is collected over water at 25°C and 1 atm. If the partial pressure of water vapor is 0.0313 atm, what is the mole \fraction of nitrogen gas?

A. 0.99

Correct B. 0.995

C. 0.998

D. 0.999

Correct Answer: B

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Question 9

A solution contains 0.1 M NaCl and 0.2 M NaNO3. What is the concentration of Cl- ions in the 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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Question 10

A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

In the context of Environmental Chemistry, what is the primary mechanism by which atmospheric sulfur dioxide (SO2) is removed from the atmosphere?

Correct A. Wet deposition

B. Dry deposition

C. Photolysis

D. Chemical reaction with ozone

Correct Answer: A

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Question 12

A sample of nitrogen gas (N2) is heated to 500 K. What is the average kinetic energy of the nitrogen molecules?

A. 1.5 kJ/mol

Correct B. 3.0 kJ/mol

C. 4.5 kJ/mol

D. 6.0 kJ/mol

Correct Answer: B

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Question 13

A 2.50 g sample of sulfur (S8) is burned in oxygen to produce sulfur dioxide (SO2). If the reaction is 95% efficient, what is the volume of SO2 produced at STP?

A. 1.25 L

Correct B. 2.50 L

C. 3.75 L

D. 5.00 L

Correct Answer: B

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Question 14

A solution contains 0.100 M sodium chloride (NaCl). What is the concentration of chloride ions \( Cl- \) in the solution?

A. 0.0500 M

Correct B. 0.100 M

C. 0.150 M

D. 0.200 M

Correct Answer: B

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Question 15

A 5.00 L sample of a gas at 25°C and 1.00 atm is compressed to 10.0 L at the same temperature. What is the new pressure?

A. 2.00 atm

B. 4.00 atm

C. 6.00 atm

Correct D. 8.00 atm

Correct Answer: D

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Question 16

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of C(s) to form CO2(g).

A. 393.5 kJ/mol

Correct B. -393.5 kJ/mol

C. 0 kJ/mol

D. 1.5 kJ/mol

Correct Answer: B

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Question 17

A 0.5 M solution of NaOH is prepared by dissolving 2.5 g of NaOH in 1 L of water. What is the molarity of the solution?

Correct A. 0.5 M

B. 1.0 M

C. 2.5 M

D. 5.0 M

Correct Answer: A

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Question 18

The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of vaporization of 1 mole of H2O(l) to form H2O(g).

Correct A. 40.7 kJ/mol

B. 80.7 kJ/mol

C. 120.7 kJ/mol

D. 160.7 kJ/mol

Correct Answer: A

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Question 19

A 2.0 M solution of HCl is prepared by dissolving 4.0 g of HCl in 1 L of water. What is the molarity of the solution?

Correct A. 2.0 M

B. 4.0 M

C. 6.0 M

D. 8.0 M

Correct Answer: A

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Question 20

The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of C(s) to form CO(g).

A. 110.5 kJ/mol

Correct B. -110.5 kJ/mol

C. 0 kJ/mol

D. -1.5 kJ/mol

Correct Answer: B

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Question 21

A 1.5 M solution of NaOH is prepared by dissolving 3.0 g of NaOH in 1 L of water. What is the molarity of the solution?

Correct A. 1.5 M

B. 3.0 M

C. 4.5 M

D. 6.0 M

Correct Answer: A

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Question 22

The s\tandard enthalpy of formation of H2(g) is 0 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of H2(g) to form H2O(g).

A. 285.8 kJ/mol

Correct B. -285.8 kJ/mol

C. 0 kJ/mol

D. -1.5 kJ/mol

Correct Answer: B

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Question 23

A 3.0 M solution of HCl is prepared by dissolving 6.0 g of HCl in 1 L of water. What is the molarity of the solution?

Correct A. 3.0 M

B. 6.0 M

C. 9.0 M

D. 12.0 M

Correct Answer: A

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Question 24

The s\tandard enthalpy of formation of O2(g) is 0 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of O2(g) to form 2 moles of CO2(g).

A. -393.5 kJ/mol

B. -787.0 kJ/mol

C. 0 kJ/mol

D. 1.5 kJ/mol

Correct Answer: VIEW ANSWER

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Question 25

A 0.1 M solution of K2Cr2O7 is prepared by dissolving 2.5 g of K2Cr2O7 in 100 mL of water. Calculate the number of moles of K2Cr2O7 used in preparing the solution.

Correct A. 0.005 mol

B. 0.01 mol

C. 0.015 mol

D. 0.02 mol

Correct Answer: A

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