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POST UTME NILE UNIVERSITY 2020 Chemistry | Objective

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Question 1 View Details

A 0.1 M solution of a weak acid HA is mixed with 0.1 M NaOH. If the resulting solution has a pH of 4.5, what is the value of the dissociation cons\tant of the acid (Ka)?

Correct A. 1.0 x 10^-5

B. 1.0 x 10^-4

C. 1.0 x 10^-3

D. 1.0 x 10^-2

Correct Answer: A

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Question 2 View Details

A diagram of a titration setup is shown below. If 25.0 mL of 0.1 M NaOH is required to reach the equivalence point, what is the concentration of the acid (HA)?

A. 0.01 M

Correct B. 0.1 M

C. 1.0 M

D. 10.0 M

Correct Answer: B

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Question 3 View Details

A 2.0 g sample of a compound is found to have a mass of 2.5 g when placed in a 10.0 mL solution of 0.1 M NaOH. What is the molar mass of the compound?

A. 50.0 g/mol

B. 100.0 g/mol

Correct C. 150.0 g/mol

D. 200.0 g/mol

Correct Answer: C

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Question 4 View Details

A diagram of a chemical apparatus is shown below. If the apparatus is used to measure the pH of a solution, what is the pH of the solution?

A. 1.0

B. 2.0

Correct C. 3.0

D. 4.0

Correct Answer: C

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Question 5 View Details

A 0.1 M solution of a weak acid HA is mixed with 0.1 M NaOH. If the resulting solution has a pH of 4.5, what is the value of the dissociation cons\tant of the acid (Ka)?

Correct A. 1.0 x 10^-5

B. 1.0 x 10^-4

C. 1.0 x 10^-3

D. 1.0 x 10^-2

Correct Answer: A

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Question 6 View Details

A reaction is carried out in a bomb calorimeter at cons\tant volume. The reaction is exothermic and releases 12.5 kJ of heat energy. If the initial temperature of the reaction mixture is 298 K, what is the change in internal energy (ΔU) for the reaction?

A. 12.5 kJ

Correct B. -12.5 kJ

C. 0 kJ

D. 25 kJ

Correct Answer: B

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Question 7 View Details

A 2.50 g sample of a metal is heated to 100°C and then dropped into 25.0 mL of water at 20.0°C. If the final temperature of the water is 22.5°C, what is the specific heat capacity of the metal?

A. 0.500 J/g°C

Correct B. 1.00 J/g°C

C. 2.00 J/g°C

D. 4.00 J/g°C

Correct Answer: B

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Question 8 View Details

A solution of 0.100 M NaCl is prepared by dissolving 6.00 g of NaCl in 1.00 L of water. What is the concentration of Cl- ions in the solution?

Correct A. 0.100 M

B. 0.200 M

C. 0.300 M

D. 0.400 M

Correct Answer: A

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Question 9 View Details

A 10.0 g sample of a metal is heated to 100°C and then dropped into 50.0 mL of water at 20.0°C. If the final temperature of the water is 22.5°C, what is the specific heat capacity of the metal?

A. 0.500 J/g°C

Correct B. 1.00 J/g°C

C. 2.00 J/g°C

D. 4.00 J/g°C

Correct Answer: B

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Question 10 View Details

A solution of 0.0500 M HCl is prepared by dissolving 2.00 g of HCl in 1.00 L of water. What is the concentration of H+ ions in the solution?

Correct A. 0.0500 M

B. 0.100 M

C. 0.200 M

D. 0.400 M

Correct Answer: A

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Question 11 View Details

A sample of a metal oxide is heated in a crucible. The resulting gas is collected over water and found to have a volume of 2.5 L at 20°C and 1.5 atm. If the gas is CO2, calculate the number of moles of CO2 produced.

A. 0.1 mol

Correct B. 0.2 mol

C. 0.3 mol

D. 0.4 mol

Correct Answer: B

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Question 12 View Details

A solution of HCl is titrated with a solution of NaOH. The initial pH of the HCl solution is 2.5. After the addition of 25 mL of NaOH solution, the pH of the solution is 3.5. Calculate the concentration of the HCl solution.

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 13 View Details

A redox reaction occurs between Fe2+ and Cr2+ ions. The reaction is as follows: Fe2+ + Cr2+ → Fe3+ + Cr3+. If 2.5 g of Fe2+ ions are added to 1.0 L of a solution containing 0.1 M Cr2+ ions, what is the concentration of Fe3+ ions produced?

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 14 View Details

A catalyst is added to a reaction mixture containing 1.0 M H2 and 1.0 M O2. The reaction is as follows: 2H2 + O2 → 2H2O. If the reaction is allowed to proceed for 10 minutes, what is the concentration of H2 remaining?

A. 0.5 M

B. 0.6 M

Correct C. 0.7 M

D. 0.8 M

Correct Answer: C

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Question 15 View Details

A solution of NH3 is prepared by dissolving 10 g of NH3 in 1.0 L of water. The pH of the solution is 9.5. Calculate the concentration of NH4+ ions present.

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 16 View Details

A sample of an ideal gas is heated from 300 K to 400 K at cons\tant volume. What is the ratio of the final pressure to the initial pressure?

Correct A. 1.33

B. 1.5

C. 2

D. 3

Correct Answer: A

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Question 17 View Details

A solution contains 10 g of glu\cose (C6H12O6) per 100 g of water. What is the molality of the solution?

A. 0.5 m

Correct B. 1 m

C. 2 m

D. 5 m

Correct Answer: B

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Question 18 View Details

A colloidal solution contains 10 g of starch in 100 g of water. What is the volume of the solution that will have a concentration of 0.1 g/mL?

A. 100 mL

B. 200 mL

Correct C. 500 mL

D. 1000 mL

Correct Answer: C

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Question 19 View Details

A sample of a gas has a volume of 2 L at a pressure of 1 atm and a temperature of 300 K. What is the volume of the gas at a pressure of 2 atm and a temperature of 400 K?

A. 4 L

B. 6 L

Correct C. 8 L

D. 10 L

Correct Answer: C

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Question 20 View Details

A solution contains 10 g of sodium chloride (NaCl) per 100 g of water. What is the molarity of the solution?

A. 0.1 M

B. 0.5 M

Correct C. 1 M

D. 2 M

Correct Answer: C

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Question 21 View Details

A 0.1 M solution of a monoprotic acid is titrated with 0.1 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the acid.

A. 1 x 10^-3 M

Correct B. 1 x 10^-4 M

C. 1 x 10^-5 M

D. 1 x 10^-6 M

Correct Answer: B

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Question 22 View Details

A 2.0 g sample of a subs\tance is dissolved in 100 mL of water. The resulting solution has a concentration of 0.02 M. Calculate the molar mass of the subs\tance.

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 23 View Details

A 1.0 M solution of a weak acid is titrated with 1.0 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the acid.

A. 1 x 10^-1 M

Correct B. 1 x 10^-2 M

C. 1 x 10^-3 M

D. 1 x 10^-4 M

Correct Answer: B

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Question 24 View Details

A 1.0 M solution of a weak base is titrated with 1.0 M HCl. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the base.

A. 1 x 10^-1 M

Correct B. 1 x 10^-2 M

C. 1 x 10^-3 M

D. 1 x 10^-4 M

Correct Answer: B

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Question 25 View Details

A 1.0 M solution of a weak acid is titrated with 1.0 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the acid.

A. 1 x 10^-1 M

Correct B. 1 x 10^-2 M

C. 1 x 10^-3 M

D. 1 x 10^-4 M

Correct Answer: B

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