POST UTME UNILORIN 2017 Chemistry | Objective

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Question 1
Determine the s\tandard Gibbs free energy change (ΔG°) for the reaction: 2NO(g) + O2(g) → 2NO2(g) at 298 K and 1 atm, given that the s\tandard enthalpy change (ΔH°) is -114.1 kJ/mol and the s\tandard entropy change (ΔS°) is -146.4 J/mol·K.
A. -114.1 kJ/mol
B. -146.4 J/mol·K
C. -114.1 kJ/mol + 298 K * \( -146.4 J/mol·K \)
D. -114.1 kJ/mol - 298 K * \( -146.4 J/mol·K \)
Question 2
Determine the molar mass of a polymer with the following structure: [-CH2-CH2-CH2-CH2-]n. Given that the repeating unit has a molecular weight of 28 g/mol, calculate the molar mass of the polymer.
A. 56 g/mol
B. 84 g/mol
C. 112 g/mol
D. 140 g/mol
Question 3
A solution contains 0.100 M NH3 and 0.0500 M HCl. What is the pH of the solution?
A. 4.00
B. 5.00
C. 6.00
D. 7.00
Question 4
A solution contains 0.5 M NaCl. If 10 mL of 1 M HCl is added to 90 mL of the solution, what is the concentration of Cl^- ions in the resulting solution?
A. 0.55 M
B. 0.5 M
C. 0.45 M
D. 0.4 M
Question 5
The diagram below shows a titration curve for the reaction between a strong acid and a weak base. What is the pH of the solution at point A?
A. 7.0
B. 8.0
C. 9.0
D. 10.0
Question 6
A 250 mL sample of a 0.500 M solution of sodium chloride (NaCl) is mixed with 250 mL of a 0.500 M solution of calcium chloride (CaCl2). What is the concentration of the resulting solution?
A. 0.250 M
B. 0.500 M
C. 0.750 M
D. 1.00 M
Question 7
A 2.00 L sample of a gas at 27°C and 1.00 atm is collected over water. If the vapor pressure of water at 27°C is 26.7 mmHg, what is the partial pressure of the gas?
A. 0.33 atm
B. 0.67 atm
C. 1.00 atm
D. 1.33 atm
Question 8
In the process of electrolysis, the cathode is typically made of a material that is less reactive than the anode. Which of the following materials is commonly used for the cathode in the electrolysis of a molten salt?
A. Graphite
B. Platinum
C. Iridium
D. Tungsten
Question 9
The s\tandard entropy of formation of CO2(g) is 213.8 J/mol*K. If 2.50 mol of CO2 is produced at 298 K, calculate the total entropy change for the reaction.
A. 531.0 J/K
B. 533.5 J/K
C. 536.0 J/K
D. 538.5 J/K
Question 10
A 100 mL sample of a 0.500 M solution of sodium hydroxide (NaOH) is mixed with 100 mL of a 0.500 M solution of hydrochloric acid (HCl). What is the concentration of the resulting solution?
A. 0.250 M
B. 0.500 M
C. 0.750 M
D. 1.00 M
Question 11
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO(g)?
A. -110.5 kJ/mol
B. -393.5 kJ/mol
C. -74.8 kJ/mol
D. -283.5 kJ/mol
Question 12
A solution of a salt has a conductivity of 1.0 x 10^-3 S/m. What is the concentration of the salt in the solution?
A. 0.1 M
B. 0.5 M
C. 1.0 M
D. 5.0 M
Question 13
In the electrolysis of a molten salt, the anode is typically made of a material that is more reactive than the cathode. Which of the following materials is commonly used for the anode in the electrolysis of a molten salt?
A. Graphite
B. Platinum
C. Iridium
D. Tungsten
Question 14
A 10.0 mL sample of 0.100 M CaCl2 is mixed with 20.0 mL of 0.0500 M NaOH. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 15
A 2.5g sample of a non-volatile solute is dissolved in 50g of water at 25°C. Calculate the molality of the solution.
A. 0.5 m
B. 1.0 m
C. 1.5 m
D. 2.0 m

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