Exam Body

Year

Subject

Paper Type

POST UTME ACHIEVERS UNIVERSITY 2018 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 2018 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1

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 0.5 M and 0.2 M, respectively, and the rate of reaction is 0.01 M/s after 10 minutes.

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

B. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)

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

D. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 2

A sample of CO2 gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of water vapor is 0.02 atm, what is the mole \fraction of CO2 in the gas mixture?

A. \( x_{CO_2} = \frac{P_{CO_2}}{P_{total}} \)

Correct B. \( x_{CO_2} = \frac{P_{CO_2} - P_{H_2O}}{P_{total}} \)

C. \( x_{CO_2} = \frac{P_{H_2O}}{P_{total}} \)

D. \( x_{CO_2} = \frac{P_{CO_2} + P_{H_2O}}{P_{total}} \)

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 3

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?

Correct A. \( V_2 = \frac{P_1 V_1 T_2}{P_2 T_1} \)

B. \( V_2 = \frac{P_2 V_1 T_1}{P_1 T_2} \)

C. \( V_2 = \frac{P_1 V_1 T_1}{P_2 T_2} \)

D. \( V_2 = \frac{P_2 V_1 T_2}{P_1 T_1} \)

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 4

A solution contains 0.1 M NaCl and 0.2 M CaCl2. What is the concentration of Cl- ions in the solution?

A. \( [Cl^-] = 0.1 M \)

B. \( [Cl^-] = 0.2 M \)

Correct C. \( [Cl^-] = 0.3 M \)

D. \( [Cl^-] = 0.4 M \)

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 5

A 10 mL sample of a solution contains 0.5 g of glu\cose. What is the concentration of glu\cose in the solution?

Correct A. \( C = \frac{m}{V} \)

B. \( C = \frac{V}{m} \)

C. \( C = \frac{m}{V^2} \)

D. \( C = \frac{V^2}{m} \)

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 6

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of C(s) + O2(g) → CO2(g) in kJ/mol.

Correct A. -393.5 kJ/mol

B. -393.5 kJ/mol + 0 kJ/mol

C. -393.5 kJ/mol - 0 kJ/mol

D. 0 kJ/mol

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 7

The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation of H2(g) + 1/2 O2(g) → H2O(l) in kJ/mol.

Correct A. -285.8 kJ/mol

B. -285.8 kJ/mol + 0 kJ/mol

C. -285.8 kJ/mol - 0 kJ/mol

D. 0 kJ/mol

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 8

The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of formation of N2(g) + 3H2(g) → 2NH3(g) in kJ/mol.

Correct A. -45.9 kJ/mol

B. -45.9 kJ/mol + 0 kJ/mol

C. -45.9 kJ/mol - 0 kJ/mol

D. 0 kJ/mol

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 9

The s\tandard enthalpy of formation of C6H12O6(s) is -1273.3 kJ/mol. Calculate the s\tandard enthalpy of formation of 6C(s) + 6H2(g) + 3O2(g) → C6H12O6(s) in kJ/mol.

Correct A. -1273.3 kJ/mol

B. -1273.3 kJ/mol + 0 kJ/mol

C. -1273.3 kJ/mol - 0 kJ/mol

D. 0 kJ/mol

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 10

The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of formation of C(s) + 1/2 O2(g) → CO(g) in kJ/mol.

Correct A. -110.5 kJ/mol

B. -110.5 kJ/mol + 0 kJ/mol

C. -110.5 kJ/mol - 0 kJ/mol

D. 0 kJ/mol

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 11

Determine the pH of a 0.1 M solution of HCl at 25°C.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 12

A 2.5 g sample of a metal carbonate is treated with 20 cm³ of 0.5 M HCl. If the reaction is complete, calculate the number of moles of CO₂ produced.

A. 0.025

B. 0.05

Correct C. 0.075

D. 0.1

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 13

The diagram below shows a titration curve for the reaction between HCl and NaOH.

A. pH 7

Correct B. pH 10

C. pH 12

D. pH 14

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 14

A 10 cm³ sample of a solution containing 0.5 M NaOH is mixed with 20 cm³ of a solution containing 0.2 M HCl. Calculate the pH of the resulting solution.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 15

The diagram below shows a simple apparatus for measuring the solubility of a gas.

Correct A. Solubility

B. Molarity

C. Moles

D. Volume

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 16

Determine the pH of a 0.1 M solution of HCl. Assume that the dissociation cons\tant of HCl is 10^\( -7 \).

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 17

A polymer is composed of 80% polyethylene and 20% polypropylene. If the density of polyethylene is 0.95 g/cm^3 and the density of polypropylene is 0.90 g/cm^3, what is the average density of the polymer?

A. 0.92

B. 0.93

Correct C. 0.94

D. 0.95

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 18

A 2.0 M solution of NaOH is titrated with a 1.0 M solution of HCl. If 25 mL of HCl is required to reach the equivalence point, what is the pH of the solution at the equivalence point?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 19

A sample of benzene (C6H6) has a mass of 10.0 g. If the molar mass of benzene is 78.0 g/mol, what is the number of moles of benzene present?

A. 0.10

Correct B. 0.20

C. 0.30

D. 0.40

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 20

A 1.0 M solution of H2SO4 is titrated with a 1.0 M solution of NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the pH of the solution at the equivalence point?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 21

A 2.50 g sample of an unknown metal carbonate is heated to produce a 1.25 g sample of the metal oxide. Calculate the percentage yield of the metal oxide, given that the molar mass of the metal carbonate is 100 g/mol and the molar mass of the metal oxide is 50 g/mol.

A. 40%

Correct B. 50%

C. 60%

D. 70%

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 22

The graph below shows the variation of pressure (P) with volume (V) for a fixed amount of gas at cons\tant temperature.

Correct A. P ∝ 1/V

B. P ∝ V

C. P ∝ 1/V^2

D. P ∝ V^2

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 23

A solution of sodium chloride (NaCl) is prepared by dissolving 35.5 g of NaCl in 250 cm^3 of water. Calculate the molarity of the solution.

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 24

A metal (X) reacts with chlorine gas to form a white solid. The reaction is as follows: 2X + Cl2 → 2XCl. If 2.5 g of X reacts with 1.5 g of Cl2, calculate the percentage yield of XCl.

A. 80%

Correct B. 90%

C. 95%

D. 98%

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 25

A 2.0 M solution of sodium hydroxide (NaOH) is prepared by dissolving 40 g of NaOH in 1.0 litre of water. Calculate the concentration of the solution in terms of molarity.

A. 1.0 M

Correct B. 2.0 M

C. 3.0 M

D. 4.0 M

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows

Help others prepare! Share this practice hub:

Chat with Support