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POST UTME IMS U 2020 Chemistry | Objective

Are you preparing for POST UTME IMS U 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

Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol, ΔHf(Ca(s)) = -178.2 kJ/mol.

Correct A. -1206.8 kJ/mol

B. -1206.9 kJ/mol

C. -1206.7 kJ/mol

D. -1206.6 kJ/mol

Correct Answer: A

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Question 2

A 2.5 M solution of H2O2 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 2 hours, and the volume of O2 gas collected is 1.2 L at 25°C and 1 atm, calculate the number of moles of O2 gas collected.

Correct A. 0.06 mol

B. 0.07 mol

C. 0.08 mol

D. 0.09 mol

Correct Answer: A

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Question 3

The reaction between CH3OH(l) and HCl(aq) is catalyzed by H+ ions. If the initial concentration of CH3OH is 0.5 M and the initial concentration of HCl is 0.2 M, calculate the concentration of CH3OH after 10 minutes if the rate cons\tant is 0.05 min^-1.

Correct A. 0.3 M

B. 0.4 M

C. 0.5 M

D. 0.6 M

Correct Answer: A

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Question 4

A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. If the resulting solution is 0.5 M in NaCl, 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 5

A 2.0 M solution of H2SO4 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 1 hour, and the volume of O2 gas collected is 0.8 L at 25°C and 1 atm, calculate the number of moles of O2 gas collected.

Correct A. 0.04 mol

B. 0.05 mol

C. 0.06 mol

D. 0.07 mol

Correct Answer: A

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Question 6

At 298 K, the s\tandard Gibbs free energy change for the reaction 2NO(g) + O2(g) → 2NO2(g) is -110 kJ/mol. Calculate the equilibrium cons\tant (K) for this reaction.

Correct A. \( e^{-\frac{-110000}{8.314 \times 298}} \)

B. \( e^{\frac{-110000}{8.314 \times 298}} \)

C. \( e^{\frac{110000}{8.314 \times 298}} \)

D. \( e^{-\frac{110000}{8.314 \times 298}} \)

Correct Answer: A

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Question 7

The diagram below shows the structure of a polymer chain. What is the type of polymerization reaction that occurred to form this chain?

Correct A. Addition polymerization

B. Condensation polymerization

C. Ring-opening polymerization

D. Step-growth polymerization

Correct Answer: A

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Question 8

A sample of nitrogen gas at 25°C and 1 atm is placed in a container with a volume of 2 L. What is the number of moles of nitrogen gas present in the container?

Correct A. \( \frac{1 \times 2}{22.4} \)

B. \( \frac{1 \times 2}{24.4} \)

C. \( \frac{1 \times 2}{20.4} \)

D. \( \frac{1 \times 2}{18.4} \)

Correct Answer: A

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Question 9

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol?

Correct A. \( -285.8 \)

B. \( -241.8 \)

C. \( -393.5 \)

D. \( -285.8 + 393.5 \)

Correct Answer: A

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Question 10

The diagram below shows the structure of a ha\logen. What is the type of bond that exists between the central atom and the outer atoms?

Correct A. Covalent bond

B. Ionic bond

C. Polar covalent bond

D. Hydrogen bond

Correct Answer: A

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Question 11

A 0.1 M solution of a weak base, B, is titrated with 0.1 M HCl. If the initial pH of the solution is 9.5, what is the pH after the addition of 20 mL of 0.1 M HCl?

A. 7.5

Correct B. 8.5

C. 9.5

D. 10.5

Correct Answer: B

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Question 12

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

Correct A. 0.01 M

B. 0.02 M

C. 0.03 M

D. 0.04 M

Correct Answer: A

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Question 13

A 1.0 M solution of a salt, NaCl, is mixed with 1.0 M HCl. 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 14

A 0.1 M solution of a weak acid, HA, is titrated with 0.1 M NaOH. If the initial pH of the solution is 3.5, what is the pH after the addition of 20 mL of 0.1 M NaOH?

A. 4.5

Correct B. 5.5

C. 6.5

D. 7.5

Correct Answer: B

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Question 15

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

A. 1.0

B. 2.0

C. 3.0

Correct D. 4.0

Correct Answer: D

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Question 16

The rate cons\tant (k) of a first-order reaction is given by the equation: k = 2.303/t \log10\( A0/A \). If the initial concentration (A0) of a reac\tant is 0.1 M and the concentration (A) after 10 minutes is 0.05 M, calculate the rate cons\tant (k) of the reaction.

Correct A. 0.0005 min^-1

B. 0.001 min^-1

C. 0.005 min^-1

D. 0.01 min^-1

Correct Answer: A

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Question 17

A 2.5 L flask contains 0.5 mol of an ideal gas at a temperature of 298 K. The gas is heated to a temperature of 373 K. Calculate the new volume of the gas, assuming that the amount of gas remains cons\tant.

A. 3.5 L

Correct B. 4.5 L

C. 5.5 L

D. 6.5 L

Correct Answer: B

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Question 18

The half-life of a radioactive subs\tance is 5 years. If the initial amount of the subs\tance is 100 g, calculate the amount of the subs\tance remaining after 20 years.

Correct A. 6.25 g

B. 12.5 g

C. 25 g

D. 50 g

Correct Answer: A

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Question 19

A solution contains 0.1 M NaCl. If 10 mL of the solution is diluted to 100 mL, what is the new concentration of the solution?

Correct A. 0.01 M

B. 0.1 M

C. 1 M

D. 10 M

Correct Answer: A

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Question 20

A 2.0 L flask contains 0.5 mol of an ideal gas at a temperature of 298 K. The gas is compressed to a volume of 1.0 L. Calculate the new temperature of the gas, assuming that the amount of gas remains cons\tant.

A. 373 K

B. 473 K

Correct C. 573 K

D. 673 K

Correct Answer: C

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Question 21

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CaCO3(s) u\sing the following reaction: CaO(s) + CO2(g) → CaCO3(s).

Correct A. -1206.5 kJ/mol

B. -1206.0 kJ/mol

C. -1207.0 kJ/mol

D. -1208.0 kJ/mol

Correct Answer: A

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Question 22

A 2.50 L flask contains 0.250 mol of an ideal gas at 25°C. Calculate the pressure of the gas u\sing the ideal gas law.

Correct A. 1.01 × 10^5 Pa

B. 1.02 × 10^5 Pa

C. 1.03 × 10^5 Pa

D. 1.04 × 10^5 Pa

Correct Answer: A

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Question 23

The boiling point of a solution containing 10.0 g of glu\cose (C6H12O6) in 100.0 g of water is 99.5°C. Calculate the molality of the solution.

Correct A. 0.500 m

B. 0.600 m

C. 0.700 m

D. 0.800 m

Correct Answer: A

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Question 24

A 25.0 mL sample of a solution containing 0.100 M NaOH is titrated with 0.100 M HCl. Calculate the number of moles of HCl required to reach the equivalence point.

Correct A. 0.00250 mol

B. 0.00275 mol

C. 0.00300 mol

D. 0.00325 mol

Correct Answer: A

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Question 25

A 50.0 mL sample of a solution containing 0.100 M NaOH is titrated with 0.100 M HCl. Calculate the pH of the solution at the equivalence point.

Correct A. 7.00

B. 7.50

C. 8.00

D. 8.50

Correct Answer: A

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