POST UTME WELLSPRING UNIVERSITY 2017 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The rate cons\tant of a first-order reaction is 0.025 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?
A. 0.05 M
B. 0.025 M
C. 0.1 M
D. 0.2 M
Question 2
Determine the pH of a 0.1 M solution of HCl. The dissociation cons\tant of HCl is 10^\( -7 \).
A. 1
B. 2
C. 3
D. 4
Question 3
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. What is the pressure of the gas?
A. 1.5 atm
B. 2.5 atm
C. 3.5 atm
D. 4.5 atm
Question 4
Determine the molar mass of a polymer with the following molecular formula: [CH2CH2]n. Assume that the polymer is composed of only carbon and hydrogen atoms.
A. 12 g/mol
B. 24 g/mol
C. 36 g/mol
D. 48 g/mol
Question 5
A sample of nitrogen gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 300 K. Calculate the number of moles of nitrogen gas present in the sample.
A. 0.1
B. 0.2
C. 0.3
D. 0.4
Question 6
A 0.1 M solution of a weak acid HA is mixed with a 0.2 M solution of a strong base NaOH. The resulting solution is 0.1 M in HA and 0.2 M in NaOH. Calculate the pH of the resulting solution.
A. \( pH = 7 \)
B. \( pH = 4 \)
C. \( pH = 9 \)
D. \( pH = 11 \)
Question 7
What is the formula for the compound formed by the reaction of nitrogen and oxygen?
A. NO
B. N2O
C. NO2
D. N2O3
Question 8
A 100.0 mL sample of a solution containing 0.100 M NaCl is titrated with 0.100 M AgNO3. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 9
A 50 mL sample of 0.2 M HCl is titrated with 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 10
The s\tandard electrode potential of the Zn^2+/Zn couple is -0.76 V. What is the s\tandard electrode potential of the Cu^2+/Cu couple if the cell potential is 0.42 V?
A. -0.18 V
B. -0.18 V
C. 0.18 V
D. 0.58 V
Question 11
A diagram of a titration setup is shown below. If 25.0 mL of 0.1 M HCl is added to 25.0 mL of 0.1 M NaOH, what is the pH of the resulting solution?
A. \( pH = 7 \)
B. \( pH = 4 \)
C. \( pH = 9 \)
D. \( pH = 11 \)
Question 12
A 50.0 g sample of a subs\tance is found to have a mass of 25.0 g after being placed in a 100.0 mL beaker and heated to 100°C. What is the molar mass of the subs\tance?
A. 50.0 g/mol
B. 75.0 g/mol
C. 100.0 g/mol
D. 125.0 g/mol
Question 13
A 2.00 L flask contains 0.500 atm of N2 gas at 298 K. If 1.00 atm of O2 gas is added to the flask, what is the total pressure of the gas mixture?
A. 1.50 atm
B. 1.75 atm
C. 2.00 atm
D. 2.25 atm
Question 14
A 10 g sample of a subs\tance is found to have a mass of 12 g when heated to 100°C. What is the molar enthalpy of vaporization of the subs\tance?
A. 40 kJ/mol
B. 50 kJ/mol
C. 60 kJ/mol
D. 70 kJ/mol
Question 15
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after the addition of 15.0 mL of NaOH.
A. 2.00
B. 3.00
C. 4.00
D. 5.00

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