POST UTME BOWEN UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The half-reaction for the oxidation of S2- to S is: S2- → S + ?
A. 2e-
B. e-
C. H2O
D. OH-
Question 2
A 1.00-L sample of a solution containing 0.100 M NaCl is mixed with 1.00 L of a solution containing 0.0500 M CaCl2. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 3
A 2.00-g sample of a subs\tance is placed in a 100-mL flask and heated to 100°C. The pressure of the gas is measured to be 1.00 atm. What is the number of moles of gas present?
A. 0.0500 mol
B. 0.0750 mol
C. 0.100 mol
D. 0.125 mol
Question 4
A 25 mL sample of 0.5 M H2SO4 is titrated with 1 M NaOH. Calculate the number of moles of NaOH required to reach the equivalence point.
A. 0.025
B. 0.05
C. 0.075
D. 0.1
Question 5
A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. Calculate the molar mass of the repeating unit.
A. 200
B. 400
C. 600
D. 800
Question 6
The s\tandard enthalpy of formation of H2O(l) is -285.83 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of C(s) if the s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol.
A. -393.5 kJ/mol
B. -393.5 kJ/mol
C. -393.5 kJ/mol
D. -393.5 kJ/mol
Question 7
Determine the rate cons\tant (k) for the first-order reaction: A → B, given that the initial concentration of A is 0.5 M and the concentration of A after 2 hours is 0.2 M. The rate cons\tant is related to the half-life \( t1/2 \) by the equation: ln(2) = kt1/2.
A. \( k = \frac{ln\( 2 \ \)}{t_{1/2}} )
B. \( k = \frac{ln\( 0.2 \ \)}{2} )
C. \( k = \frac{0.5 - 0.2}{2} \)
D. \( k = \frac{0.2}{0.5} \)
Question 8
The half-reaction for the reduction of Cu2+ to Cu is: Cu2+ + e- → Cu+ + ?
A. Cu
B. Cu2+
C. e-
D. H+
Question 9
A 1 M solution of NaOH is titrated with 1 M HCl. Calculate the pH of the solution at the equivalence point.
A. 7
B. 8
C. 9
D. 10
Question 10
A 2.00-L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?
A. 0.970 atm
B. 0.975 atm
C. 0.980 atm
D. 0.985 atm
Question 11
A gas is collected over water at 25°C and 1 atm. If the volume of the gas is 2.5 L, and the vapor pressure of water at 25°C is 0.0313 atm, calculate the partial pressure of the gas.
A. \( P_{gas} = P_{total} - P_{H2O} \)
B. \( P_{gas} = P_{total} + P_{H2O} \)
C. \( P_{gas} = \frac{P_{total} - P_{H2O}}{2} \)
D. \( P_{gas} = \frac{P_{total} + P_{H2O}}{2} \)
Question 12
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H2CO3(s) given that the s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol and the s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol.
A. -685.8
B. -695.8
C. -705.8
D. -715.8
Question 13
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4
Question 14
A polymer is composed of repeating units of the following structure: CH2-CH2-CH2-CH2. If the polymer has a molecular weight of 100,000 g/mol, and the repeating unit has a molecular weight of 28 g/mol, calculate the degree of polymerization (DP).
A. \( DP = \frac{M_n}{M_0} \)
B. \( DP = \frac{M_0}{M_n} \)
C. \( DP = \frac{M_n}{M_0 \times 28} \)
D. \( DP = \frac{28}{M_n} \)
Question 15
A solution of 0.1 M NaCl is prepared by dissolving 1.0 g of NaCl in 100 mL of water. If the density of the solution is 1.0 g/mL, calculate the concentration of NaCl in the solution.
A. \( C = \frac{m}{V} \)
B. \( C = \frac{V}{m} \)
C. \( C = \frac{m}{V \times d} \)
D. \( C = \frac{V \times d}{m} \)

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