POST UTME ACHIEVERS UNIVERSITY 2018 Chemistry | Objective

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. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
C. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)
D. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
Question 2
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 3
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.
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
Question 4
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 5
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 6
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. \( [Cl^-] = 0.4 M \)
Question 7
What is the pH of a 0.1 M solution of HCl?
A. 1
B. 2
C. 3
D. 4
Question 8
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
D. 4
Question 9
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
B. 0.20
C. 0.30
D. 0.40
Question 10
Determine the pH of a 0.1 M solution of HCl at 25°C.
A. 1
B. 2
C. 3
D. 4
Question 11
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 12
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 13
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.
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
Question 14
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.
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
Question 15
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
D. 4

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