POST UTME CRAWFORD UNIVERSITY 2017 Chemistry | Objective

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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. \( k = \frac{0.01}{0.5 \times 0.2 \times 10} \)
B. \( k = \frac{0.01}{0.5 \times 0.2 \times 20} \)
C. \( k = \frac{0.01}{0.5 \times 0.2 \times 30} \)
D. \( k = \frac{0.01}{0.5 \times 0.2 \times 40} \)
Question 2
A solution contains 0.1 M NaOH and 0.2 M HCl. Determine the pH of the solution after mixing 10 mL of each solution.
A. \( pH = -\log[H^+] \)
B. \( pH = -\log[OH^-] \)
C. \( pH = \log[H^+] \)
D. \( pH = \log[OH^-] \)
Question 3
A 2.5 L flask contains 0.5 mol of an ideal gas at 25°C. Calculate the pressure of the gas u\sing the ideal gas law.
A. \( P = \frac{nRT}{V} \)
B. \( P = \frac{nRT}{2V} \)
C. \( P = \frac{nRT}{3V} \)
D. \( P = \frac{nRT}{4V} \)
Question 4
A 1.5 L flask contains 0.2 mol of an ideal gas at 30°C. Calculate the volume of the gas at 40°C u\sing Charles' Law.
A. \( V_2 = \frac{V_1 T_2}{T_1} \)
B. \( V_2 = \frac{V_1 T_1}{T_2} \)
C. \( V_2 = \frac{V_1 T_1^2}{T_2} \)
D. \( V_2 = \frac{V_1 T_1}{T_2^2} \)
Question 5
A 25 mL sample of a solution containing 0.01 M CuSO4 is titrated with 0.01 M Na2S. Determine the number of moles of S2- ions required to react with 25 mL of the CuSO4 solution.
A. \( n_{S2^-} = \frac{0.01 \times 25}{1000} \)
B. \( n_{S2^-} = \frac{0.01 \times 25}{500} \)
C. \( n_{S2^-} = \frac{0.01 \times 25}{2000} \)
D. \( n_{S2^-} = \frac{0.01 \times 25}{3000} \)

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