POST UTME ACHIEVERS UNIVERSITY 2018 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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
C. 0.3 M
D. 0.4 M
Question 2
A 2.5 g sample of a non-metallic element is heated in a crucible until it is completely vaporized. If the volume of the vapor is 2.5 L at 25°C and 1 atm, what is the molar mass of the element?
A. 20 g/mol
B. 30 g/mol
C. 40 g/mol
D. 50 g/mol
Question 3
A 10 mL sample of a solution contains 0.5 g of glu\cose. What is the concentration of glu\cose in the solution?
A. \( C = \frac{m}{V} \)
B. \( C = \frac{V}{m} \)
C. \( C = \frac{m}{V^2} \)
D. \( C = \frac{V^2}{m} \)
Question 4
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
C. 0.075
D. 0.1
Question 5
What is the pH of a 0.1 M solution of HCl?
A. 1
B. 2
C. 3
D. 4
Question 6
The diagram below shows a simple apparatus for measuring the solubility of a gas.
A. Solubility
B. Molarity
C. Moles
D. Volume
Question 7
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%
B. 50%
C. 60%
D. 70%
Question 8
The diagram below shows a titration curve for the reaction between HCl and NaOH.
A. pH 7
B. pH 10
C. pH 12
D. pH 14
Question 9
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.
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
Question 10
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 11
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
D. 4
Question 12
A 2.5 L sample of a gas at 25°C and 1 atm is compressed to 1/5 of its original volume. What is the new pressure?
A. 5 atm
B. 10 atm
C. 15 atm
D. 20 atm
Question 13
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?
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. \( V_2 = \frac{P_2 V_1 T_2}{P_1 T_1} \)
Question 14
The graph below shows the variation of pressure (P) with volume (V) for a fixed amount of gas at cons\tant temperature.
A. P ∝ 1/V
B. P ∝ V
C. P ∝ 1/V^2
D. P ∝ V^2
Question 15
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. \( [Cl^-] = 0.2 M \)
C. \( [Cl^-] = 0.3 M \)
D. \( [Cl^-] = 0.4 M \)

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