Practice post utme uniosun chemistry 2024 Past Questions

Question 1

The element with atomic number 12 is classified as a metal in the periodic table. Which of the following is a characteristic of this element?

Correct A. It is a good conductor of electricity.

B. It is a poor conductor of electricity.

C. It is a noble gas.

D. It is a ha\logen.

Correct Answer: A

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Question 2

A sample of a metal oxide is heated in a crucible. The resulting gas is collected and its volume is measured at different temperatures. Which of the following is a correct interpretation of the data?

Correct A. The volume of the gas increases with increa\sing temperature.

B. The volume of the gas decreases with increa\sing temperature.

C. The volume of the gas remains cons\tant with increa\sing temperature.

D. The volume of the gas increases with decrea\sing temperature.

Correct Answer: A

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Question 3

A polymer is a long chain of repeating units. Which of the following is a characteristic of a polymer?

A. It has a high melting point.

Correct B. It has a low melting point.

C. It is a good conductor of electricity.

D. It is a poor conductor of electricity.

Correct Answer: B

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Question 4

A solution of a non-metallic oxide is prepared by dissolving the oxide in water. Which of the following is a correct interpretation of the data?

Correct A. The solution is acidic.

B. The solution is basic.

C. The solution is neutral.

D. The solution is a salt.

Correct Answer: A

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Question 5

A gas is collected over water in a gas syringe. Which of the following is a correct interpretation of the data?

Correct A. The volume of the gas is directly proportional to the temperature.

B. The volume of the gas is inversely proportional to the temperature.

C. The volume of the gas is directly proportional to the pressure.

D. The volume of the gas is inversely proportional to the pressure.

Correct Answer: A

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Question 6

The reaction of chlorine gas with sodium hydroxide solution is a classic example of a redox reaction. Write the balanced chemical equation for this reaction and identify the oxidation and reduction half-reactions.

A. 2NaOH + Cl2 → NaCl + NaClO + H2O

Correct B. 2NaOH + Cl2 → NaClO + NaCl + H2O

C. 2NaOH + Cl2 → NaCl + NaClO3 + H2O

D. 2NaOH + Cl2 → NaClO + NaClO3 + H2O

Correct Answer: B

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Question 7

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 methane (CH4(g)) u\sing the following equation: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l).

Correct A. -890.3 kJ/mol

B. -890.4 kJ/mol

C. -890.5 kJ/mol

D. -890.6 kJ/mol

Correct Answer: A

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Question 8

A 0.1 M solution of sodium sulfate (Na2SO4) is prepared by dissolving 2.5 g of the salt in 100 mL of water. Calculate the molarity of the solution.

A. 0.025 M

B. 0.05 M

Correct C. 0.1 M

D. 0.2 M

Correct Answer: C

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Question 9

A diagram of a simple electrolytic cell is shown below. Identify the anode and cathode.

Correct A. A is the anode and B is the cathode

B. A is the cathode and B is the anode

C. A is the anode and B is the electrolyte

D. A is the electrolyte and B is the cathode

Correct Answer: A

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Question 10

A diagram of a simple chromatography setup is shown below. Identify the stationary phase and the mobile phase.

Correct A. A is the stationary phase and B is the mobile phase

B. A is the mobile phase and B is the stationary phase

C. A is the stationary phase and B is the solvent

D. A is the solvent and B is the stationary phase

Correct Answer: A

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Question 11

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.20 L at 25°C and 1 atm. The volume of H2O produced is 0.50 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 12

A solution contains 5.00 g of NaCl in 100.0 mL of water. Calculate the molarity of the solution.

A. 0.50 M

Correct B. 1.00 M

C. 2.00 M

D. 3.00 M

Correct Answer: B

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Question 13

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.20 L at 25°C and 1 atm. The volume of H2O produced is 0.50 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 14

A solution contains 5.00 g of NaCl in 100.0 mL of water. Calculate the molarity of the solution.

A. 0.50 M

Correct B. 1.00 M

C. 2.00 M

D. 3.00 M

Correct Answer: B

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Question 15

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.20 L at 25°C and 1 atm. The volume of H2O produced is 0.50 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 16

A solution contains 5.00 g of NaCl in 100.0 mL of water. Calculate the molarity of the solution.

A. 0.50 M

Correct B. 1.00 M

C. 2.00 M

D. 3.00 M

Correct Answer: B

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Question 17

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.20 L at 25°C and 1 atm. The volume of H2O produced is 0.50 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

Correct A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: A

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Question 18

A solution contains 5.00 g of NaCl in 100.0 mL of water. Calculate the molarity of the solution.

A. 0.50 M

Correct B. 1.00 M

C. 2.00 M

D. 3.00 M

Correct Answer: B

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Question 19

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The volume of CO2 produced is 1.20 L at 25°C and 1 atm. The volume of H2O produced is 0.50 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

A. C2H6

B. C3H8

C. C4H10

D. C5H12

Correct Answer: VIEW ANSWER

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Question 20

A mixture of 0.5 mol of NaCl and 0.2 mol of KNO3 is dissolved in 1 L of water. Calculate the molar concentration of Cl- ions in the solution.

A. 0.5 M

Correct B. 0.6 M

C. 0.7 M

D. 0.8 M

Correct Answer: B

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Question 21

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. The mass of the metal oxide produced is 2.0 g. Calculate the percentage yield of the metal oxide.

A. 80%

B. 85%

Correct C. 90%

D. 95%

Correct Answer: C

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Question 22

A 10 mL sample of a solution containing 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.

A. 5 mL

Correct B. 10 mL

C. 15 mL

D. 20 mL

Correct Answer: B

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Question 23

A 5.0 g sample of a metal hydroxide is dissolved in 50 mL of water to produce a solution containing 0.1 M OH- ions. Calculate the molar concentration of the metal 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 24

A 2.0 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. The mass of the metal oxide produced is 1.5 g. Calculate the percentage yield of the metal oxide.

A. 75%

B. 80%

Correct C. 85%

D. 90%

Correct Answer: C

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Question 25

A 10 mL sample of a solution containing 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.

A. 5 mL

Correct B. 10 mL

C. 15 mL

D. 20 mL

Correct Answer: B

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