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POST UTME UI 2024 Chemistry | Objective

Are you preparing for POST UTME UI exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2024 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, ΔHf(Ca(s)) = -178.2 kJ/mol.

Correct A. -1206.7 kJ/mol

B. -1206.8 kJ/mol

C. -1206.9 kJ/mol

D. -1207.0 kJ/mol

Correct Answer: A

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Question 2

A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.

A. 1.01 x 10^5 Pa

Correct B. 2.02 x 10^5 Pa

C. 3.03 x 10^5 Pa

D. 4.04 x 10^5 Pa

Correct Answer: B

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Question 3

A 10% solution of NaOH is prepared by dissolving 10 g of NaOH in 90 g of water. Calculate the molarity 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 4

A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.

A. 1.01 x 10^5 Pa

Correct B. 2.02 x 10^5 Pa

C. 3.03 x 10^5 Pa

D. 4.04 x 10^5 Pa

Correct Answer: B

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Question 5

A 10% solution of NaOH is prepared by dissolving 10 g of NaOH in 90 g of water. Calculate the molarity 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 6

Determine the number of moles of ΔHg in 250 mL of a 0.5 M solution of Hg(NO3)2.

A. 0.25 mol

Correct B. 0.5 mol

C. 1.0 mol

D. 1.25 mol

Correct Answer: B

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Question 7

A 2.5 L flask contains 0.5 mol of CO2 at 25°C. Calculate the partial pressure of CO2 in the flask.

A. 0.5 atm

Correct B. 1.0 atm

C. 1.5 atm

D. 2.0 atm

Correct Answer: B

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Question 8

A sample of a polymer has a molecular weight of 50,000 g/mol. If 0.5 g of the polymer is dissolved in 100 mL of solvent, calculate the concentration of the solution in g/L.

A. 0.1 g/L

B. 0.5 g/L

Correct C. 1.0 g/L

D. 5.0 g/L

Correct Answer: C

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Question 9

A 10% solution of a pesticide is to be diluted to 1% concentration. If 250 mL of the 10% solution is to be diluted to 1 L, calculate the amount of water required.

A. 250 mL

Correct B. 500 mL

C. 750 mL

D. 1000 mL

Correct Answer: B

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Question 10

A 2.0 L flask contains 0.5 mol of H2 at 25°C. Calculate the volume of the flask that would contain 0.25 mol of H2 at the same temperature.

A. 1.0 L

Correct B. 1.5 L

C. 2.0 L

D. 2.5 L

Correct Answer: B

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Question 11

A mixture of 0.5 mol of CO and 0.3 mol of H2 is heated to 500 K in a 1 L vessel. Assuming ideal gas behavior, calculate the partial pressure of CO.

Correct A. 0.5 atm

B. 1.0 atm

C. 1.5 atm

D. 2.0 atm

Correct Answer: A

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Question 12

A 2.0 g sample of a metal is dissolved in 50 mL of 1 M HCl. The resulting solution is then titrated with 0.1 M NaOH. If the volume of NaOH required to reach the equivalence point is 20 mL, 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 13

A 100 mL sample of a solution containing 0.5 M NaCl is mixed with 100 mL of 0.5 M CaCl2. What is the concentration of the resulting solution?

A. 0.5 M

B. 1.0 M

Correct C. 1.5 M

D. 2.0 M

Correct Answer: C

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Question 14

A 2.0 g sample of a metal is heated in a crucible until it melts. The resulting liquid is then poured into a mold and allowed to cool. If the resulting solid has a volume of 5.0 mL, what is its density?

A. 5.0 g/mL

Correct B. 10.0 g/mL

C. 15.0 g/mL

D. 20.0 g/mL

Correct Answer: B

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Question 15

A 100 mL sample of a solution containing 0.5 M NaOH is mixed with 100 mL of 0.5 M HCl. What is the resulting pH?

A. 0

B. 1

C. 2

Correct D. 7

Correct Answer: D

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Question 16

Determine the molar mass of a polymer with the following composition: 30% polyethylene (C2H4), 40% polypropylene (C3H6), and 30% polystyrene (C8H8).

A. 100 g/mol

Correct B. 150 g/mol

C. 200 g/mol

D. 250 g/mol

Correct Answer: B

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Question 17

A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 1.0 L of water. 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 18

A 2.0 L flask contains 1.0 atm of O2 at 298 K. What is the partial pressure of O2 in the flask?

A. 0.5 atm

Correct B. 1.0 atm

C. 1.5 atm

D. 2.0 atm

Correct Answer: B

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Question 19

A 10.0 g sample of a hydrocarbon is burned in a bomb calorimeter, relea\sing 35.0 kJ of heat. What is the molar mass of the hydrocarbon?

A. 50 g/mol

B. 100 g/mol

Correct C. 150 g/mol

D. 200 g/mol

Correct Answer: C

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Question 20

A 0.1 M solution of HCl is prepared by dissolving 3.0 g of HCl in 1.0 L of water. What is the pH of the solution?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 21

The reaction of cyclohexane with bromine in the presence of light produces a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?

A. 1,2-dibromocyclohexane

Correct B. 1,4-dibromocyclohexane

C. cis-1,2-dibromocyclohexane

D. trans-1,2-dibromocyclohexane

Correct Answer: B

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Question 22

A 2.50 g sample of an unknown metal oxide is heated in a crucible until it decomposes completely. The mass of the metal obtained is 1.75 g. What is the empirical formula of the metal oxide?

A. MgO

B. CaO

Correct C. Fe2O3

D. CuO

Correct Answer: C

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Question 23

A solution containing 0.100 M NaOH is mixed with a solution containing 0.0500 M HCl. What is the concentration of the resulting solution?

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

A 25.0 mL sample of a 0.100 M solution of NaOH is mixed with a 25.0 mL sample of a 0.0500 M solution of HCl. What is the pH of the resulting solution?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 25

A 1.00 g sample of a metal is heated in a crucible until it decomposes completely. The mass of the metal obtained is 0.750 g. What is the empirical formula of the metal?

A. Mg

B. Ca

Correct C. Fe

D. Cu

Correct Answer: C

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