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POST UTME ACHIEVERS UNIVERSITY 2022 Chemistry | Objective

Are you preparing for POST UTME ACHIEVERS UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2022 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

The polymerization of styrene to polystyrene is an example of a ______ reaction.

A. Condensation

Correct B. Addition

C. Substitution

D. Elimination

Correct Answer: B

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Question 2

The compound with the molecular formula SO2Cl2 is an example of a ______.

Correct A. Oxidizing Agent

B. Reducing Agent

C. Acid Chloride

D. Ester

Correct Answer: A

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Question 3

The reaction 2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(s) is an example of a ______ reaction.

Correct A. Redox

B. Synthesis

C. Decomposition

D. Single Displacement

Correct Answer: A

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Question 4

The equilibrium cons\tant expression for the reaction N2(g) + O2(g) ⇌ 2NO(g) is Kc = [NO]^2 / [N2][O2].

Correct A. Kc = [NO]^2 / [N2][O2]

B. Kc = [NO] / [N2][O2]

C. Kc = [NO]^2 / [O2]

D. Kc = [N2][O2] / [NO]

Correct Answer: A

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Question 5

The rate cons\tant for a reaction is 0.05 s^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?

A. 0.05 M

B. 0.1 M

Correct C. 0.2 M

D. 0.5 M

Correct Answer: C

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Question 6

The electrolysis of a solution of silver nitrate (AgNO3) in water produces silver metal and nitrogen dioxide gas. Write the half-equation for the oxidation of silver ions at the anode.

A. \text{Ag}^+ + \text{e}^- \rightarrow \text{Ag}

B. \text{Ag}^+ + \text{H}_2\text{O} \rightarrow \text{Ag} + \text{H}^+

Correct C. \text{Ag}^+ + \frac{1}{2} \text{H}_2\text{O} \rightarrow \text{Ag} + \frac{1}{2} \text{H}_2\text{O} + \text{e}^-

D. \text{Ag}^+ + \text{e}^- \rightarrow \text{Ag} + \text{H}^+

Correct Answer: C

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Question 7

A 0.1 M solution of sodium chloride (NaCl) is electrolyzed u\sing a platinum electrode. What is the mass of chlorine gas produced at the anode after 2 hours?

A. 0.5 g

Correct B. 1.0 g

C. 1.5 g

D. 2.0 g

Correct Answer: B

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Question 8

A colloidal solution of gold (Au) is prepared by the reduction of gold chloride (HAuCl4) u\sing sodium borohydride (NaBH4). What is the name of the process?

A. Precipitation

Correct B. Reduction

C. Nucleation

D. Coagulation

Correct Answer: B

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Question 9

A metal (M) reacts with hydrochloric acid (HCl) to produce hydrogen gas and a salt. The reaction is as follows: \text{M} + 2\text{HCl} \rightarrow \text{MCl}_2 + \text{H}_2. What is the name of the metal?

Correct A. Zinc (Zn)

B. Iron (Fe)

C. Copper (Cu)

D. Silver (Ag)

Correct Answer: A

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Question 10

A 1.0 M solution of sulfuric acid (H2SO4) is mixed with a 1.0 M solution of sodium hydroxide (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 11

Determine the number of moles of oxygen gas (O2) produced when 2.5 moles of hydrogen peroxide (H2O2) decompose according to the equation: 2H2O2(l) → 2H2O(l) + O2(g).

Correct A. 1.25 moles

B. 2.5 moles

C. 3.75 moles

D. 5 moles

Correct Answer: A

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Question 12

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

A. 7.00

Correct B. 7.25

C. 7.50

D. 8.00

Correct Answer: B

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Question 13

The half-life of a radioactive subs\tance is 5.0 days. If 100.0 mg of the subs\tance initially exists, how much will remain after 20.0 days?

Correct A. 12.5 mg

B. 25.0 mg

C. 50.0 mg

D. 100.0 mg

Correct Answer: A

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Question 14

A solution contains 0.100 M CaCl2 and 0.100 M Na2SO4. What is the concentration of Ca2+ ions in the solution?

Correct A. 0.0500 M

B. 0.100 M

C. 0.150 M

D. 0.200 M

Correct Answer: A

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Question 15

A 2.00 L flask contains 0.200 mol of CO2 at 25°C. What is the pressure of the gas?

A. 0.500 atm

Correct B. 1.00 atm

C. 1.50 atm

D. 2.00 atm

Correct Answer: B

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Question 16

Determine the pH of a 0.1 M solution of HCl.

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 17

A 25 mL sample of 0.5 M H2SO4 is titrated with 0.5 M NaOH. Calculate the number of moles of H2SO4.

A. 0.125

Correct B. 0.25

C. 0.5

D. 1

Correct Answer: B

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Question 18

The diagram below shows a titration setup. Identify the burette.

Correct A.

Correct Answer: A

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Question 19

Calculate the molar mass of a compound that contains 40% carbon and 60% oxygen by mass.

A. 60

B. 80

Correct C. 100

D. 120

Correct Answer: C

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Question 20

The diagram below shows a chemical apparatus setup. Identify the part labeled A.

Correct A.

Correct Answer: A

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Question 21

A polymer is formed by the condensation reaction between two monomers, A and B. If 2.5 g of A and 3.2 g of B are used, and the molecular weight of A is 120 g/mol and that of B is 180 g/mol, what is the number of moles of the polymer formed?

A. 0.021 mol

B. 0.025 mol

Correct C. 0.032 mol

D. 0.040 mol

Correct Answer: C

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Question 22

A solution of NaCl is prepared by dissolving 35 g of NaCl in 250 mL of water. What is the molarity of the solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: B

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Question 23

A colloidal solution of starch in water is prepared by adding 2 g of starch to 100 mL of water. What is the concentration of the solution in terms of mass percentage?

A. 2%

Correct B. 5%

C. 10%

D. 15%

Correct Answer: B

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Question 24

The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O?

Correct A. -285.8 kJ/mol

B. -393.5 kJ/mol

C. -483.6 kJ/mol

D. -583.7 kJ/mol

Correct Answer: A

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Question 25

A sample of a gas occupies a volume of 2.5 L at a pressure of 1.2 atm. What is the pressure of the gas if its volume is reduced to 1.5 L?

A. 2.4 atm

Correct B. 2.8 atm

C. 3.2 atm

D. 3.6 atm

Correct Answer: B

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