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POST UTME KSU 2021 Chemistry | Objective

Are you preparing for POST UTME KSU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2021 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1

A polymer is formed by the condensation reaction between a diol and a diisocyanate. The reaction is represented by the equation:

A. The polymer is a thermoplastic.

Correct B. The polymer is a thermoset.

C. The polymer is a elastomer.

D. The polymer is a ceramic.

Correct Answer: B

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Question 2

A metal is extracted from its ore through a process involving the reduction of the metal oxide with carbon. The reaction is represented by the equation:

A. The metal is iron.

B. The metal is copper.

Correct C. The metal is zinc.

D. The metal is lead.

Correct Answer: C

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Question 3

A non-metal is a subs\tance that is brittle and has a high ionization energy. Which of the following non-metals has a high ionization energy?

A. Nitrogen (N2)

B. Oxygen (O2)

Correct C. Fluorine (F2)

D. Chlorine (Cl2)

Correct Answer: C

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Question 4

A solution is a homogeneous mixture of two or more subs\tances. Which of the following is an example of a solution?

A. A mixture of sand and water.

Correct B. A mixture of sugar and water.

C. A mixture of salt and water.

D. A mixture of oil and water.

Correct Answer: B

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Question 5

A base is a subs\tance that is a strong electrolyte and has a pH greater than 7. Which of the following is a base?

Correct A. Sodium hydroxide (NaOH)

B. Sodium chloride (NaCl)

C. Sodium carbonate (Na2CO3)

D. Sodium sulfate (Na2SO4)

Correct Answer: A

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Question 6

At 298 K, the s\tandard Gibbs free energy change (ΔG°) for the reaction 2NO(g) + O2(g) → 2NO2(g) is -111.3 kJ/mol. Calculate the equilibrium cons\tant (K) for this reaction.

Correct A. 1.2 × 10^11

B. 1.2 × 10^9

C. 1.2 × 10^7

D. 1.2 × 10^5

Correct Answer: A

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Question 7

The half-life of a radioactive subs\tance is 5.3 years. If the initial amount of the subs\tance is 100 g, how much of the subs\tance will remain after 21.4 years?

A. 10 g

Correct B. 20 g

C. 30 g

D. 40 g

Correct Answer: B

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Question 8

A solution contains 0.5 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the new concentration of NaCl?

A. 0.05 M

Correct B. 0.1 M

C. 0.2 M

D. 0.5 M

Correct Answer: B

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Question 9

The s\tandard enthalpy of formation (ΔH°f) for CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion (ΔH°c) for 1 mol of C(s) at 298 K.

Correct A. -393.5 kJ/mol

B. -393.5 kJ/mol + 298 kJ/mol

C. -393.5 kJ/mol - 298 kJ/mol

D. -393.5 kJ/mol + 298 kJ/mol + 298 kJ/mol

Correct Answer: A

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Question 10

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is added, what is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

The reaction of cyclohexane with bromine in the presence of light yields 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-1,4-dibromocyclohexane

Correct Answer: B

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Question 12

A metal M reacts with chlorine gas to form a white solid product. The reaction is accompanied by a release of heat. What is the most likely identity of the metal M?

Correct A. Ca

B. Mg

C. Al

D. Zn

Correct Answer: A

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Question 13

A polymer is made up of repeating units of the following structure: CH2=CH-COOH. What is the name of this polymer?

A. Polyethylene

B. Polypropylene

C. Polyvinyl alcohol

Correct D. Polyacrylic acid

Correct Answer: D

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Question 14

A solution of sodium chloride is added to a solution of silver nitrate. What is the precipitate formed?

Correct A. AgCl

B. NaNO3

C. NaCl

D. AgNO3

Correct Answer: A

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Question 15

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 solution

B. To measure the concentration of the solution

C. To mix the solution with the analyte

D. To separate the solution from the analyte

Correct Answer: A

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Question 16

Determine the pH of a 0.1 M solution of HCl in water at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \).

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 17

A 2.5 g sample of a polymer is dissolved in 100 mL of a solvent. If the density of the solution is 1.2 g/mL, what is the molar mass of the polymer?

A. 1000 g/mol

B. 2000 g/mol

Correct C. 5000 g/mol

D. 10000 g/mol

Correct Answer: C

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Question 18

A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. What is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 19

A 2.0 g sample of a non-metallic element is heated in a crucible until it melts. If the mass of the crucible and the melted element is 2.5 g, what is the molar mass of the element?

A. 50 g/mol

B. 100 g/mol

Correct C. 200 g/mol

D. 500 g/mol

Correct Answer: C

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Question 20

A 1.0 M solution of H2SO4 is mixed with a 1.0 M solution of NaOH. What is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 21

Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentrations of NO and O2 are 0.1 M and 0.2 M, respectively, and the rate of reaction is 0.05 M/s after 10 minutes.

Correct A. \( k = \frac{2.303}{t} \log left\( \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \right \ \) )

B. \( k = \frac{2.303}{t} \log left\( \frac{[NO]_t [O_2]_t}{[NO]_0 [O_2]_0} \right \ \) )

C. \( k = \frac{2.303}{t} \log left\( \frac{[NO]_0 [O_2]_0}{[NO]_t [O_2]_t} \right \ \) )

D. \( k = \frac{2.303}{t} \log left\( \frac{[NO]_t [O_2]_t}{[NO]_0 [O_2]_0} \right \ \) )

Correct Answer: A

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Question 22

A 0.1 M solution of NaOH is titrated with 0.1 M HCl. The pH of the solution at the equivalence point is 7. Calculate the pH of the solution at the half-equivalence point.

Correct A. \( pH = \frac{1}{2} \times pH_{eq} \)

B. \( pH = \frac{1}{2} \times pH_{initial} \)

C. \( pH = pH_{eq} - \frac{1}{2} \times pH_{initial} \)

D. \( pH = pH_{eq} + \frac{1}{2} \times pH_{initial} \)

Correct Answer: A

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Question 23

A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl2 → MCl2. If 2.5 g of M reacts with 1.5 g of Cl2, what is the percentage yield of MCl2?

Correct A. \( % yield = \frac{mass of MCl_2 produced}{theoretical mass of MCl_2} \times 100% \)

B. \( % yield = \frac{mass of M used}{theoretical mass of MCl_2} \times 100% \)

C. \( % yield = \frac{mass of Cl_2 used}{theoretical mass of MCl_2} \times 100% \)

D. \( % yield = \frac{mass of MCl_2 produced}{mass of M used} \times 100% \)

Correct Answer: A

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Question 24

A solution of 0.1 M NaOH is titrated with 0.1 M HCl. The pH of the solution at the equivalence point is 7. Calculate the pH of the solution at the half-equivalence point.

Correct A. \( pH = \frac{1}{2} \times pH_{eq} \)

B. \( pH = \frac{1}{2} \times pH_{initial} \)

C. \( pH = pH_{eq} - \frac{1}{2} \times pH_{initial} \)

D. \( pH = pH_{eq} + \frac{1}{2} \times pH_{initial} \)

Correct Answer: A

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Question 25

A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl2 → MCl2. If 2.5 g of M reacts with 1.5 g of Cl2, what is the percentage yield of MCl2?

Correct A. \( % yield = \frac{mass of MCl_2 produced}{theoretical mass of MCl_2} \times 100% \)

B. \( % yield = \frac{mass of M used}{theoretical mass of MCl_2} \times 100% \)

C. \( % yield = \frac{mass of Cl_2 used}{theoretical mass of MCl_2} \times 100% \)

D. \( % yield = \frac{mass of MCl_2 produced}{mass of M used} \times 100% \)

Correct Answer: A

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