POST UTME REDEEMERS UNIVERSITY 2022 Chemistry | Objective

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Question 1
The s\tandard Gibbs free energy change (ΔG°) for the reaction: 2NO(g) + O2(g) → 2NO2(g) is -120 kJ/mol. What is the equilibrium cons\tant (K) for the reaction?
A. 1.0 x 10^\( -6 \)
B. 1.0 x 10^\( -3 \)
C. 1.0 x 10^\( -1 \)
D. 1.0 x 10^3
Question 2
A 2.5 M solution of hydrochloric acid (HCl) is prepared by dissolving 125 g of HCl in 250 mL of water. What is the concentration of the solution in moles per liter (M)?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 3
A 1.0 M solution of a weak acid, HA, has a pH of 4.5. What is the concentration of the acid if the pH is decreased to 3.5 by the addition of 20 cm³ of 0.1 M NaOH?
A. 0.5 M
B. 0.75 M
C. 1.0 M
D. 1.25 M
Question 4
The diagram below represents a titration setup. What is the purpose of the burette in this setup?
A. To measure the volume of the solution
B. To mix the solution with the analyte
C. To add the titrant to the analyte
D. To measure the pH of the solution
Question 5
A 2.0 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide is 1.5 g, what is the molar mass of the metal carbonate?
A. 100 g/mol
B. 150 g/mol
C. 200 g/mol
D. 250 g/mol
Question 6
The half-life of a radioactive subs\tance is 5 days. If 100 mg of the subs\tance is present initially, how much of the subs\tance will remain after 20 days?
A. 50 mg
B. 25 mg
C. 12.5 mg
D. 6.25 mg
Question 7
A 10.0 mL sample of a solution containing 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after the titration?
A. 7
B. 8
C. 9
D. 10
Question 8
A 2.50 M solution of sodium hydroxide (NaOH) is prepared by dissolving 50.0 g of NaOH in 1.00 L of water. What is the concentration of the solution in terms of molarity?
A. 1.00 M
B. 2.00 M
C. 2.50 M
D. 5.00 M
Question 9
A sample of 1.0 L of a gas at 2.0 atm and 25°C is allowed to expand to 2.0 L. What is the final pressure of the gas?
A. 1.0 atm
B. 1.5 atm
C. 2.0 atm
D. 2.5 atm
Question 10
The diagram below shows a titration setup. If 25.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH, what is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 11
The reaction of chlorine gas with sodium hydroxide solution is a classic example of a redox reaction. Write the balanced chemical equation for this reaction, including the state of each subs\tance.
A. 2NaOH + Cl2 → NaCl + NaClO + H2O
B. 2NaOH + Cl2 → NaClO + NaCl + H2O
C. 2NaOH + Cl2 → NaCl + H2O
D. 2NaOH + Cl2 → NaClO + H2O
Question 12
The s\tandard reduction potential of the Cu2+/Cu couple is +0.34 V. What is the s\tandard reduction potential of the Ag+/Ag couple if the s\tandard reduction potential of the Ag+/Ag couple is +0.80 V?
A. +0.46 V
B. +0.50 V
C. +0.54 V
D. +0.58 V
Question 13
The rate cons\tant (k) of a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/\( mol*K \), and the temperature (T) is 298 K, what is the value of the rate cons\tant (k) if the pre-exponential factor (A) is 2.5 x 10^10 s^\( -1 \)?
A. 1.2 x 10^\( -4 \) s^\( -1 \)
B. 1.2 x 10^\( -3 \) s^\( -1 \)
C. 1.2 x 10^\( -2 \) s^\( -1 \)
D. 1.2 x 10^\( -1 \) s^\( -1 \)
Question 14
A 2.50 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 1.75 g, calculate the mass of carbon dioxide gas produced.
A. 1.25 g
B. 1.75 g
C. 2.00 g
D. 2.50 g
Question 15
A sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the volume of the gas is 2.5 L, what is the partial pressure of the nitrogen gas?
A. 0.95
B. 0.98
C. 1.00
D. 1.02

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