Practice post utme joseph ayo babalola university chemistry 2024 Past Questions

Question 1

The electronegativity of an element is a measure of its ability to attract electrons in a covalent bond. Which of the following elements has the highest electronegativity among the given options?

Correct A. Fluorine (F)

B. Chlorine (Cl)

C. Bromine (Br)

D. Iodine (I)

Correct Answer: A

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Question 2

A 2.5 M solution of sodium hydroxide (NaOH) is prepared by dissolving 12.5 g of NaOH in water to make 1 L of solution. What is the molarity of the solution?

A. 0.25 M

Correct B. 0.3125 M

C. 0.5 M

D. 0.625 M

Correct Answer: B

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Question 3

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

Correct A. To measure the volume of the titrant

B. To measure the volume of the analyte

C. To mix the titrant and analyte

D. To separate the titrant and analyte

Correct Answer: A

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Question 4

The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is initially present, how much of the subs\tance will remain after 10 years?

A. 12.5 g

Correct B. 25 g

C. 50 g

D. 100 g

Correct Answer: B

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Question 5

A diagram of a simple black and white chemistry apparatus showing a titration setup is shown below. What is the purpose of the burette in this setup?

Correct A. To measure the volume of the titrant

B. To measure the volume of the analyte

C. To mix the titrant and analyte

D. To separate the titrant and analyte

Correct Answer: A

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Question 6

Determine the molar mass of a polymer with the following composition: 60% polyethylene (C2H4), 20% polypropylene (C3H6), and 20% polystyrene (C8H8).

A. 60 g/mol

Correct B. 120 g/mol

C. 180 g/mol

D. 240 g/mol

Correct Answer: B

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Question 7

A solution of 0.1 M NaOH is mixed with a solution of 0.1 M HCl. What is the pH of the resulting solution?

A. 1

Correct B. 7

C. 10

D. 14

Correct Answer: B

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Question 8

A sample of a gas at 25°C and 1 atm is compressed to 2 atm. What is the new volume of the gas?

A. 0.5 L

B. 1 L

Correct C. 2 L

D. 4 L

Correct Answer: C

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Question 9

A solution of 0.1 M HCl is mixed with a solution of 0.1 M NaOH. What is the resulting concentration of HCl?

Correct A. 0.05 M

B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: A

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Question 10

A sample of a solid at 25°C is heated to 100°C. What is the change in entropy?

A. 10 J/K

B. 20 J/K

Correct C. 30 J/K

D. 40 J/K

Correct Answer: C

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Question 11

The reaction between zinc metal and copper(II) sulfate solution is a classic example of a \single displacement reaction. Write the balanced chemical equation for this reaction.

Correct A. Zn + CuSO4 → ZnSO4 + Cu

B. Zn + CuSO4 → ZnSO4 + Cu2O

C. Zn + CuSO4 → ZnSO4 + CuSO3

D. Zn + CuSO4 → ZnSO4 + Cu(OH)2

Correct Answer: A

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Question 12

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

A. 7

Correct B. 7.5

C. 8

D. 9

Correct Answer: B

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Question 13

A diagram of a simple electrolytic cell is shown below. What is the purpose of the salt bridge in this cell?

A. To complete the circuit

Correct B. To prevent the buildup of charge

C. To facilitate the flow of ions

D. To increase the voltage of the cell

Correct Answer: B

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Question 14

The reaction between hydrogen gas and chlorine gas is a classic example of a synthesis reaction. Write the balanced chemical equation for this reaction.

Correct A. H2 + Cl2 → HCl

B. H2 + Cl2 → HCl2

C. H2 + Cl2 → HClO

D. H2 + Cl2 → HClO2

Correct Answer: A

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Question 15

A 10.0 g sample of a hydrocarbon is burned in a combustion reaction. The resulting carbon dioxide gas is collected and found to have a volume of 22.5 L at 25°C and 1.00 atm. What is the empirical formula of the hydrocarbon?

A. CH4

Correct B. C2H6

C. C3H8

D. C4H10

Correct Answer: B

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Question 16

A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. The initial pH of the acid solution is 3. If 20 mL of NaOH is added, the pH of the solution increases to 4.5. What is the number of moles of HA present in 1 L of the initial acid solution?

Correct A. 0.02 mol

B. 0.03 mol

C. 0.04 mol

D. 0.05 mol

Correct Answer: A

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Question 17

A metal M (atomic number 23) reacts with chlorine gas to form a white solid. The white solid is found to be soluble in water and gives a yellow solution. What is the name of the metal M?

Correct A. V

B. Cr

C. Mn

D. Fe

Correct Answer: A

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Question 18

A 2.5 L flask contains 0.5 mol of an ideal gas at a temperature of 300 K. If the gas is heated to 400 K, what is the new volume of the gas?

A. 2.5 L

Correct B. 3.33 L

C. 4 L

D. 5 L

Correct Answer: B

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Question 19

A 0.1 M solution of a salt MX is prepared by dissolving 0.1 mol of the salt in 1 L of water. If the pH of the solution is 7, what is the value of pKa of the salt?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 20

A 1 L flask contains 0.5 mol of an ideal gas at a temperature of 300 K. If the gas is compressed to half its original volume, what is the new pressure of the gas?

A. 1 atm

Correct B. 2 atm

C. 3 atm

D. 4 atm

Correct Answer: B

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Question 21

A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. The initial pH of the acid solution is 3. If 20 mL of NaOH is added, the pH of the solution increases to 4.5. What is the number of moles of HA present in 1 L of the initial acid solution?

Correct A. 0.02 mol

B. 0.03 mol

C. 0.04 mol

D. 0.05 mol

Correct Answer: A

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Question 22

A metal M (atomic number 23) reacts with chlorine gas to form a white solid. The white solid is found to be soluble in water and gives a yellow solution. What is the name of the metal M?

A. V

B. Cr

C. Mn

D. Fe

Correct Answer: VIEW ANSWER

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Question 23

A 0.1 M solution of a weak acid HA is mixed with a 0.1 M solution of a weak base BOH. If the initial concentrations of HA and BOH are 0.1 M, and the initial concentrations of H+ and OH- are negligible, what is the pH of the resulting solution after the reaction is complete?

Correct A. 4

B. 6

C. 7

D. 9

Correct Answer: A

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Question 24

A sample of a non-metallic element has a mass of 2.5 g and a volume of 5.0 mL. If the density of the element is 3.5 g/mL, what is the molar mass of the element?

A. 10

B. 20

Correct C. 30

D. 40

Correct Answer: C

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Question 25

A 2.0 M solution of a strong acid HA is mixed with a 2.0 M solution of a strong base BOH. If the initial concentrations of HA and BOH are 2.0 M, and the initial concentrations of H+ and OH- are negligible, what is the pH of the resulting solution after the reaction is complete?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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