POST UTME ACHIEVERS UNIVERSITY 2017 Chemistry | Objective

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Question 1
A solution of sodium chloride is electrolyzed u\sing a copper electrode. The anode reaction is:
A. 2Cl⁻ → Cl₂ + 2e⁻
B. 2Cl⁻ → Cl₂ + 2e⁻
C. 2Cl⁻ → Cl₂ + 2e⁻
D. 2Cl⁻ → Cl₂ + 2e⁻
Question 2
A 2.5 M solution of sodium hydroxide (NaOH) is prepared by dissolving 12.5 g of NaOH in 1 L of water. What is the molarity of the solution?
A. 2.0 M
B. 2.5 M
C. 3.0 M
D. 3.5 M
Question 3
The reaction between sodium hydroxide and hydrochloric acid is represented by the equation: 2NaOH + HCl -> NaCl + 2H2O. If 25.0 cm^3 of 0.100 M NaOH is mixed with 25.0 cm^3 of 0.100 M HCl, calculate the number of moles of NaCl produced.
A. 0.005 mol
B. 0.010 mol
C. 0.015 mol
D. 0.020 mol
Question 4
A metal ion has a charge of +3 and a radius of 100pm. What is the number of electrons in the ion?
A. 3
B. 6
C. 9
D. 12
Question 5
A chemical reaction has a rate cons\tant of 2.5s^-1. If the reaction is first-order, what is the half-life of the reaction?
A. 0.1s
B. 0.2s
C. 0.5s
D. 1.0s
Question 6
The equilibrium cons\tant for the reaction 2NO(g) ⇌ N2(g) + O2(g) is 1.0 × 10^-3 at 25°C. What is the equilibrium cons\tant for the reaction N2(g) + O2(g) ⇌ 2NO(g)?
A. 1.0 × 10^3
B. 1.0 × 10^-3
C. 1.0 × 10^-6
D. 1.0 × 10^6
Question 7
The reaction between hydrogen gas and chlorine gas is represented by the equation: H2(g) + Cl2(g) → 2HCl(g). What is the limiting reac\tant if 2.0 g of H2 is reacted with 3.0 g of Cl2?
A. H2
B. Cl2
C. Neither
D. Both
Question 8
A solution of sodium hydroxide is titrated with a solution of hydrochloric acid. The pH of the solution at the equivalence point is 7.
A. NaOH + HCl → NaCl + H₂O
B. NaOH + HCl → NaCl + H₂O
C. NaOH + HCl → NaCl + H₂O
D. NaOH + HCl → NaCl + H₂O
Question 9
The environmental impact of a chemical reaction can be determined by its Gibbs free energy change. Which of the following reactions has a negative Gibbs free energy change?
A. 2H2 + O2 → 2H2O
B. 2H2 + O2 → 2H2O2
C. 2H2 + O2 → 2H2O2
D. 2H2 + O2 → 2H2O
Question 10
A colloidal solution of silver is prepared by the reduction of silver nitrate with sodium citrate. The resulting particles have a diameter of 10 nm.
A. AgNO₃ + 3NaC₆H₅O₇ → Ag + 3NaNO₃ + 3C₆H₅O₇
B. AgNO₃ + 3NaC₆H₅O₇ → Ag + 3NaNO₃ + 3C₆H₅O₇
C. AgNO₃ + 3NaC₆H₅O₇ → Ag + 3NaNO₃ + 3C₆H₅O₇
D. AgNO₃ + 3NaC₆H₅O₇ → Ag + 3NaNO₃ + 3C₆H₅O₇
Question 11
A solution contains 2.5g of NaCl in 250mL of water. What is the molarity of the solution?
A. 0.1M
B. 0.2M
C. 0.3M
D. 0.4M
Question 12
At 25°C, 1.00 L of a gas at 2.00 atm exerts a pressure of 2.00 atm. What is the volume of the gas at 4.00 atm and 25°C?
A. 0.500 L
B. 1.00 L
C. 2.00 L
D. 4.00 L
Question 13
A 0.5 M solution of HCl is mixed with a 0.5 M solution of NaOH. The reaction is carried out in a calorimeter. If the temperature of the solution increases by 5°C, what is the value of ΔS for the reaction?
A. -50 J/K
B. -50 J/K
C. -50 J/K
D. -50 J/K
Question 14
A 10.0 g sample of a metal hydroxide is dissolved in water to produce a solution with a pH of 10.5. Calculate the concentration of the metal hydroxide.
A. 0.0010 M
B. 0.010 M
C. 0.100 M
D. 1.00 M
Question 15
The electrolysis of a solution of copper(II) sulfate u\sing a copper electrode results in the formation of copper metal at the cathode. Write the half-equation for the reduction reaction at the cathode.
A. Cu²⁺ + 2e⁻ → Cu
B. Cu + 2e⁻ → Cu²⁺
C. Cu²⁺ + 2e⁻ → Cu
D. Cu + 2e⁻ → Cu²⁺

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