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POST UTME UNIPORT 2020 Chemistry | Objective

Are you preparing for POST UTME UNIPORT exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

A mixture of 0.500 g of glu\cose (C6H12O6) and 0.250 g of fructose (C6H12O6) is dissolved in 50.0 mL of water. Calculate the molarity of the solution.

A. 0.0500 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 2

The reaction between hydrogen peroxide (H2O2) and potassium iodide (KI) is catalyzed by iodide ions \( I- \). The rate law for this reaction is given by rate = k[H2O2][I-]. If the initial concentrations of H2O2 and I- are 0.100 M and 0.0500 M, respectively, and the rate cons\tant (k) is 1.00 x 10^-3 M^-1 s^-1, calculate the initial rate of reaction.

A. 1.00 x 10^-5 M s^-1

B. 5.00 x 10^-5 M s^-1

Correct C. 1.00 x 10^-4 M s^-1

D. 5.00 x 10^-4 M s^-1

Correct Answer: C

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Question 3

A 2.00 L sample of a gas at 25.0°C and 1.00 atm is collected over water at 25.0°C. If the vapor pressure of water at 25.0°C is 23.8 torr, calculate the partial pressure of the gas.

A. 0.976 atm

Correct B. 0.987 atm

C. 0.997 atm

D. 1.00 atm

Correct Answer: B

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Question 4

A 25.0 mL sample of a 0.100 M solution of sodium hydroxide (NaOH) is titrated with a 0.100 M solution of hydrochloric acid (HCl). If 25.0 mL of HCl is required to reach the equivalence point, calculate the number of moles of NaOH in the original solution.

A. 0.00250 mol

Correct B. 0.00500 mol

C. 0.00750 mol

D. 0.0100 mol

Correct Answer: B

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Question 5

A 2.00 g sample of a polymer is dissolved in 100.0 mL of a solvent. If the solution has a vis\cosity of 1.50 cP, calculate the number-average molecular weight (Mn) of the polymer.

A. 5000 g/mol

Correct B. 10000 g/mol

C. 15000 g/mol

D. 20000 g/mol

Correct Answer: B

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Question 6

In a redox reaction, what is the role of the oxidizing agent?

A. To donate electrons

Correct B. To accept electrons

C. To facilitate the transfer of electrons

D. To inhibit the reaction

Correct Answer: B

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Question 7

What is the primary difference between a saturated and an unsaturated hydrocarbon?

Correct A. Saturated hydrocarbons have a \single bond between carbon atoms, while unsaturated hydrocarbons have multiple bonds

B. Saturated hydrocarbons have multiple bonds between carbon atoms, while unsaturated hydrocarbons have a \single bond

C. Saturated hydrocarbons are more stable than unsaturated hydrocarbons

D. Unsaturated hydrocarbons are more stable than saturated hydrocarbons

Correct Answer: A

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Question 8

A sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. What is the partial pressure of the nitrogen gas?

Correct A. 0.95 atm

B. 1.05 atm

C. 1.10 atm

D. 1.15 atm

Correct Answer: A

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Question 9

What is the expected product of the reaction between sulfuric acid and sodium hydroxide?

Correct A. Sodium sulfate

B. Sulfuric acid

C. Sodium hydroxide

D. Water

Correct Answer: A

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Question 10

A solution contains 2.5 g of sodium chloride per 100 mL of solution. What is the molarity of the solution?

A. 0.25 M

Correct B. 0.50 M

C. 0.75 M

D. 1.00 M

Correct Answer: B

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Question 11

In a redox reaction, what is the role of the oxidizing agent?

A. To gain electrons

Correct B. To lose electrons

C. To facilitate the transfer of electrons

D. To prevent the reaction from occurring

Correct Answer: B

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Question 12

A sample of iron(II) sulfate is heated to produce iron(III) oxide and sulfur trioxide. What is the balanced chemical equation for this reaction?

Correct A. \( 2FeSO_4\( s \ \) \rightarrow Fe_2O_3(s) + SO_3(g) )

B. \( FeSO_4\( s \ \) \rightarrow Fe_2O_3(s) + SO_3(g) )

C. \( 2FeSO_4\( s \ \) \rightarrow 2Fe_2O_3(s) + 2SO_3(g) )

D. \( FeSO_4\( s \ \) \rightarrow Fe_2O_3(s) + SO_2(g) )

Correct Answer: A

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Question 13

What is the primary function of the polymerization reaction in the production of polyethylene?

Correct A. To create a long chain of ethylene molecules

B. To produce a mixture of ethylene and other hydrocarbons

C. To break down ethylene into its constituent elements

D. To convert ethylene into a different type of polymer

Correct Answer: A

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Question 14

A solution of sodium hydroxide is added to a solution of copper(II) sulfate. What is the resulting precipitate?

Correct A. Copper(II) hydroxide

B. Sodium sulfate

C. Copper(II) oxide

D. Sodium copper oxide

Correct Answer: A

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Question 15

What is the primary difference between a solid and a liquid?

Correct A. A solid has a fixed shape and volume, while a liquid has a fixed volume but not a fixed shape

B. A solid has a fixed volume but not a fixed shape, while a liquid has a fixed shape and volume

C. A solid has a fixed shape and volume, while a liquid has neither a fixed shape nor a fixed volume

D. A solid has neither a fixed shape nor a fixed volume, while a liquid has a fixed shape and volume

Correct Answer: A

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Question 16

The rate cons\tant (k) of a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/mol*K, and the temperature (T) is 300 K, what is the value of the pre-exponential factor (A) if the rate cons\tant (k) is 0.05 s^-1?

Correct A. 1.67 x 10^10 s^-1

B. 1.67 x 10^8 s^-1

C. 1.67 x 10^6 s^-1

D. 1.67 x 10^4 s^-1

Correct Answer: A

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Question 17

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after the addition of 20 mL of NaOH?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 18

The half-life of a radioactive subs\tance is 5 years. If the initial activity is 1000 Bq, what is the activity after 10 years?

A. 125 Bq

Correct B. 250 Bq

C. 500 Bq

D. 1000 Bq

Correct Answer: B

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Question 19

A metal (M) reacts with chlorine gas to form a white solid. The reaction is: 2M + Cl2 → 2MCl. If 2.5 g of M reacts with 1.5 g of Cl2, what is the percentage yield of MCl?

Correct A. 80%

B. 90%

C. 95%

D. 98%

Correct Answer: A

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Question 20

A solution of 0.1 M H2SO4 is titrated with 0.1 M NaOH. What is the pH of the solution after the addition of 20 mL of NaOH?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 21

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the volume of HCl in liters?

Correct A. 0.02 L

B. 0.02 mL

C. 0.2 L

D. 0.2 mL

Correct Answer: A

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Question 22

A sample of CO2 is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of CO2 is 0.5 atm, what is the mole \fraction of CO2?

Correct A. 0.5

B. 0.25

C. 0.75

D. 0.9

Correct Answer: A

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Question 23

A 2.0 M solution of H2SO4 is mixed with 1.0 M solution of NaOH. If 20 mL of H2SO4 is added to 20 mL of NaOH, what is the pH of the resulting solution?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 24

A sample of O2 is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of O2 is 0.75 atm, what is the mole \fraction of O2?

Correct A. 0.75

B. 0.5

C. 0.25

D. 0.9

Correct Answer: A

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Question 25

A 1.0 M solution of HCl is titrated with 1.0 M NaOH. If 10 mL of NaOH is required to reach the equivalence point, what is the volume of HCl in liters?

Correct A. 0.01 L

B. 0.1 L

C. 0.1 mL

D. 0.01 mL

Correct Answer: A

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