POST UTME BOWEN UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 M solution of HCl is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 2 hours, and the volume of H2 gas produced is 2.5 L at 25°C and 1 atm, calculate the number of moles of H2 gas produced.
A. \( n = \frac{PV}{RT} \)
B. \( n = \frac{V}{22.4} \)
C. \( n = \frac{2.5}{22.4} \)
D. \( n = \frac{2.5 \times 1}{22.4} \)
Question 2
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 3
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 4
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 5
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 6
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 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
A 2.50-g sample of a compound containing only C, H, and O is analyzed by combustion. The CO2 produced is 1.25 g, and the H2O produced is 0.500 g. What is the empirical formula of the compound?
A. C2H4O2
B. C2H6O
C. C3H6O
D. C4H8O2
Question 9
The half-reaction for the oxidation of S2- to S is: S2- → S + ?
A. 2e-
B. e-
C. H2O
D. OH-
Question 10
Determine the number of moles of ΔH2O formed when 2.50 g of H2SO4 reacts with 3.00 g of NaOH in a reaction that proceeds to completion.
A. 0.0500 mol
B. 0.0750 mol
C. 0.100 mol
D. 0.125 mol
Question 11
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 12
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. \( C = \frac{V \times d}{m} \)
Question 13
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 14
The half-reaction for the reduction of Cu2+ to Cu is: Cu2+ + e- → Cu+ + ?
A. Cu
B. Cu2+
C. e-
D. H+
Question 15
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows
Help others prepare! Share this practice hub: