Practice Post UTME CHRISTOPHER UNIVERSITY chemistry 2021 Past Questions

Question 1 View Details

Determine the pH of a 0.1 M solution of HCl at 25°C. The dissociation cons\tant of HCl is 10^\( -7 \).

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 2 View Details

A diagram of a titration setup is shown below. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, 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 3 View Details

A solution contains 0.1 M HCl and 0.1 M NaOH. What is the pH of the solution after 25 mL of 0.1 M HCl is added to 25 mL of 0.1 M NaOH?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 4 View Details

A diagram of a periodic table is shown below. Identify the element with atomic number 8.

Correct A. Oxygen

B. Nitrogen

C. Carbon

D. Hydrogen

Correct Answer: A

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Question 5 View Details

A diagram of a gas law setup is shown below. If the pressure of a gas is doubled and the temperature is tripled, what is the new volume of the gas?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 6 View Details

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. -1207.6 kJ/mol

C. -1207.6 kJ/mol

D. -1207.6 kJ/mol

Correct Answer: A

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Question 7 View Details

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

Correct A. 0.5 M

B. 0.5 M

C. 0.5 M

D. 0.5 M

Correct Answer: A

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Question 8 View Details

The solubility of AgCl in water is 1.2 × 10^\( -5 \) M at 25°C. What is the concentration of Ag+ ions in a saturated solution?

Correct A. 1.2 × 10^\( -5 \) M

B. 1.2 × 10^\( -5 \) M

C. 1.2 × 10^\( -5 \) M

D. 1.2 × 10^\( -5 \) M

Correct Answer: A

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Question 9 View Details

A sample of a gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 298 K. What is the volume of the gas at a pressure of 3.0 atm and a temperature of 323 K?

Correct A. 3.2 L

B. 3.2 L

C. 3.2 L

D. 3.2 L

Correct Answer: A

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Question 10 View Details

The s\tandard enthalpy of formation of CO2(g) is -393.51 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 11 View Details

Determine the number of moles of oxygen gas (O2) produced at s\tandard temperature and pressure (STP) when 2.5 moles of hydrogen gas (H2) react with oxygen gas according to the equation: 2H2 + O2 → 2H2O.

A. 1.25 moles

B. 2.5 moles

Correct C. 5.0 moles

D. 10.0 moles

Correct Answer: C

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Question 12 View Details

A 2.5 M solution of HCl is titrated with a 1.0 M solution of NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the number of moles of HCl in the original solution?

A. 0.0625 moles

Correct B. 0.125 moles

C. 0.25 moles

D. 0.5 moles

Correct Answer: B

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Question 13 View Details

The reaction between H2 and O2 to form H2O is exothermic. If 5.0 moles of H2 react with oxygen gas to form 10.0 moles of H2O, what is the change in entropy (ΔS) for the reaction?

A. -20 J/K

B. -40 J/K

Correct C. -60 J/K

D. -80 J/K

Correct Answer: C

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Question 14 View Details

A 1.0 M solution of NaOH is titrated with a 2.0 M solution of HCl. If 25 mL of HCl is required to reach the equivalence point, what is the number of moles of NaOH in the original solution?

A. 0.125 moles

Correct B. 0.25 moles

C. 0.5 moles

D. 1.0 moles

Correct Answer: B

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Question 15 View Details

The reaction between H2 and O2 to form H2O is exothermic. If 10.0 moles of H2 react with oxygen gas to form 20.0 moles of H2O, what is the change in entropy (ΔS) for the reaction?

A. -40 J/K

B. -60 J/K

Correct C. -80 J/K

D. -100 J/K

Correct Answer: C

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Question 16 View Details

A 0.1 M solution of a monoprotic acid is titrated with 0.1 M NaOH. If the initial pH of the acid is 2.5, what is the pH after the addition of 20 mL of NaOH?

A. 3.5

B. 4.5

Correct C. 5.5

D. 6.5

Correct Answer: C

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Question 17 View Details

A 10 mL sample of a solution containing a mixture of NaCl and Na2SO4 is electrolyzed u\sing a current of 2 A for 5 minutes. If the initial concentration of Na+ ions is 0.1 M, what is the concentration of Na+ ions after electrolysis?

A. 0.05 M

B. 0.1 M

Correct C. 0.15 M

D. 0.2 M

Correct Answer: C

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Question 18 View Details

A 2 L sample of a gas at 300 K and 1 atm is expanded to 5 L at cons\tant temperature. What is the new pressure of the gas?

A. 0.2 atm

B. 0.4 atm

Correct C. 0.6 atm

D. 0.8 atm

Correct Answer: C

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Question 19 View Details

A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. If the initial pH of the acid is 3.5, what is the pH after the addition of 20 mL of NaOH?

A. 4.5

Correct B. 5.5

C. 6.5

D. 7.5

Correct Answer: B

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Question 20 View Details

A 10 mL sample of a solution containing a mixture of NaCl and Na2SO4 is electrolyzed u\sing a current of 2 A for 5 minutes. If the initial concentration of Na+ ions is 0.1 M, what is the concentration of Na+ ions after electrolysis?

A. 0.05 M

B. 0.1 M

Correct C. 0.15 M

D. 0.2 M

Correct Answer: C

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Question 21 View Details

In a reaction between zinc metal and copper(II) sulfate solution, the reaction is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 2.50 g of zinc metal is added to 100 mL of 0.100 M copper(II) sulfate solution, what is the limiting reac\tant?

Correct A. Zinc metal

B. Copper(II) sulfate solution

C. Zinc sulfate solution

D. Copper metal

Correct Answer: A

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Question 22 View Details

A 1.00 L sample of a gas at 27°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?

A. 1.00 atm

Correct B. 0.980 atm

C. 1.02 atm

D. 1.05 atm

Correct Answer: B

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Question 23 View Details

A solution contains 0.0500 M FeCl3 and 0.0500 M NaOH. What is the concentration of Fe(OH)3 formed after the reaction is complete?

A. 0.0500 M

B. 0.100 M

Correct C. 0.150 M

D. 0.200 M

Correct Answer: C

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Question 24 View Details

A 2.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?

A. 1.00 atm

Correct B. 0.980 atm

C. 1.02 atm

D. 1.05 atm

Correct Answer: B

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Question 25 View Details

A 1.00 L sample of a gas at 27°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?

A. 1.00 atm

Correct B. 0.980 atm

C. 1.02 atm

D. 1.05 atm

Correct Answer: B

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