Practice post utme eksu chemistry 2019 Past Questions

Question 1

Determine the pH of a 0.1 M solution of HCl.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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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.

A. 1.5 atm

B. 2.0 atm

Correct C. 2.5 atm

D. 3.0 atm

Correct Answer: C

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Question 3

A 25% solution of NaOH is mixed with a 10% solution of HCl. What is the resulting concentration of the solution?

A. 15%

Correct B. 20%

C. 25%

D. 30%

Correct Answer: B

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Question 4

A diagram of a titration setup is shown below. What is the purpose of the burette?

Correct A. To measure the volume of the acid

B. To measure the volume of the base

C. To mix the acid and base

D. To measure the pH of the solution

Correct Answer: A

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Question 5

A diagram of a gas law setup is shown below. What is the relationship between the variables?

Correct A. P1V1 = P2V2

B. P1V1 = T2V2

C. P1V1 = n2V2

D. P1V1 = m2V2

Correct Answer: A

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Question 6

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide formed is 2.1 g, calculate the percentage yield of the metal oxide.

A. 60%

B. 70%

Correct C. 80%

D. 90%

Correct Answer: C

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Question 7

A solution of sodium hydroxide (NaOH) is titrated with a solution of hydrochloric acid (HCl). If 25 cm^3 of 0.1 M HCl is required to neutralize 20 cm^3 of 0.2 M NaOH, calculate the concentration of the HCl 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 8

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide formed is 2.1 g, calculate the percentage yield of the metal oxide.

A. 60%

B. 70%

Correct C. 80%

D. 90%

Correct Answer: C

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Question 9

A solution of sodium hydroxide (NaOH) is titrated with a solution of hydrochloric acid (HCl). If 25 cm^3 of 0.1 M HCl is required to neutralize 20 cm^3 of 0.2 M NaOH, calculate the concentration of the HCl 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 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide formed is 2.1 g, calculate the percentage yield of the metal oxide.

A. 60%

B. 70%

Correct C. 80%

D. 90%

Correct Answer: C

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Question 11

In a redox reaction, what is the role of the catalyst in the electrolysis of water?

A. To increase the rate of reaction

B. To decrease the rate of reaction

Correct C. To facilitate the transfer of electrons

D. To increase the voltage required for electrolysis

Correct Answer: C

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Question 12

A solution contains 2.5 g of NaCl. If 25 mL of the solution is taken, what is the concentration of NaCl in the solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.5 M

D. 1.0 M

Correct Answer: B

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Question 13

A colloidal solution of starch in water is prepared. What is the nature of the particles in the solution?

A. Large particles

Correct B. Small particles

C. Spherical particles

D. Irregularly shaped particles

Correct Answer: B

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Question 14

A polymer is a long chain of molecules. What is the repeating unit in the polymer called?

A. Monomer

B. Polymer

Correct C. Repeating unit

D. Chain molecule

Correct Answer: C

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Question 15

A sample of air contains 21% oxygen, 78% nitrogen, and 1% other gases. What is the partial pressure of oxygen in the air?

Correct A. 0.21 atm

B. 0.21 kPa

C. 21% of total pressure

D. 21% of atmospheric pressure

Correct Answer: A

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Question 16

Determine the s\tandard Gibbs free energy change (ΔG°) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that ΔH° = -114.1 kJ/mol and ΔS° = -146.3 J/mol·K.

A. -114.1 kJ/mol

B. -146.3 kJ/mol

Correct C. -114.1 kJ/mol - 146.3 J/mol·K

D. -114.1 kJ/mol + 146.3 J/mol·K

Correct Answer: C

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Question 17

A 0.500 M solution of NaOH is prepared by dissolving 25.0 g of NaOH in 1.00 L of water. What is the pH of the solution?

A. 13.0

Correct B. 13.5

C. 14.0

D. 14.5

Correct Answer: B

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Question 18

The reaction: 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant (k) of 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the activation energy (Ea) for the reaction?

A. 50.0 kJ/mol

B. 60.0 kJ/mol

Correct C. 70.0 kJ/mol

D. 80.0 kJ/mol

Correct Answer: C

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Question 19

A 1.00 M solution of HCl is prepared by dissolving 37.0 g of HCl in 1.00 L of water. What is the concentration of H+ ions in the solution?

A. 0.500 M

B. 0.750 M

Correct C. 1.00 M

D. 1.25 M

Correct Answer: C

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Question 20

The reaction: 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant (k) of 2.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the half-life \( t1/2 \) for the reaction?

Correct A. 1.00 × 10^\( -2 \) s

B. 1.00 × 10^\( -3 \) s

C. 1.00 × 10^\( -4 \) s

D. 1.00 × 10^\( -5 \) s

Correct Answer: A

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Question 21

Determine the number of moles of oxygen gas (O2) required to react completely with 2.50 moles of carbon monoxide (CO) according to the equation: 2CO + O2 → 2CO2.

Correct A. 1.25 moles

B. 2.50 moles

C. 5.00 moles

D. 7.50 moles

Correct Answer: A

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Question 22

A sample of nitrogen gas (N2) occupies a volume of 2.00 liters at a pressure of 1.00 atm and a temperature of 298 K. Calculate the number of moles of nitrogen gas present, assuming ideal gas behavior.

A. 0.010 mol

Correct B. 0.020 mol

C. 0.030 mol

D. 0.040 mol

Correct Answer: B

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Question 23

A 25.0-mL sample of sulfuric acid (H2SO4) has a concentration of 0.500 M. Calculate the number of moles of sulfuric acid present.

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 24

The boiling point of a solution containing 10.0 g of glu\cose (C6H12O6) in 100.0 g of water is 102.5°C. Calculate the molality of the solution.

A. 0.500 m

Correct B. 1.00 m

C. 1.50 m

D. 2.00 m

Correct Answer: B

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Question 25

A 50.0-mL sample of a 0.500 M solution of sodium chloride (NaCl) is diluted to a total volume of 100.0 mL. Calculate the new concentration of the solution.

A. 0.250 M

Correct B. 0.500 M

C. 0.750 M

D. 1.00 M

Correct Answer: B

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