POST UTME OSUSTECH 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A sample of 1.0 g of an unknown hydrocarbon is burned in a bomb calorimeter, relea\sing 12.5 kJ of heat. What is the molar mass of the hydrocarbon?
A. 30 g/mol
B. 40 g/mol
C. 50 g/mol
D. 60 g/mol
Question 2
Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol, and ΔHf(C(s)) = 0 kJ/mol.
A. -1206.60 kJ/mol
B. -1206.19 kJ/mol
C. -1206.79 kJ/mol
D. -1206.99 kJ/mol
Question 3
A polymer chain consists of 100 monomers, each with a molecular weight of 100 g/mol. If the polymer chain has a degree of polymerization of 50, what is the number-average molecular weight of the polymer?
A. 100 g/mol
B. 200 g/mol
C. 500 g/mol
D. 1000 g/mol
Question 4
A 1.00 L flask contains 0.250 mol of an ideal gas at 300 K. Calculate the volume of the gas at 400 K u\sing Charles' Law.
A. 1.33 L
B. 1.32 L
C. 1.31 L
D. 1.30 L
Question 5
The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 2.5 g of C(s) at 298 K.
A. -275.625 kJ
B. -275.75 kJ
C. -275.875 kJ
D. -276.0 kJ
Question 6
A solution of 2.0 g of NaCl in 100 mL of water has a boiling point elevation of 0.50°C. What is the molar mass of NaCl?
A. 58.5 g/mol
B. 74.5 g/mol
C. 108.5 g/mol
D. 142.5 g/mol
Question 7
A 0.1 M solution of FeCl3 is mixed with a 0.1 M solution of NaOH. If the initial temperature of both solutions is 25°C, what is the final temperature of the mixture after complete reaction?
A. 25°C
B. 30°C
C. 35°C
D. 40°C
Question 8
A 2.00 L flask contains 0.150 M H2SO4. What is the concentration of sulfuric acid (H2SO4) in the flask if 0.500 M NaOH is added to the flask?
A. 0.0750 M
B. 0.150 M
C. 0.225 M
D. 0.300 M
Question 9
A 2.50 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.01 × 10^5 Pa
B. 2.02 × 10^5 Pa
C. 3.03 × 10^5 Pa
D. 4.04 × 10^5 Pa
Question 10
A solution of sodium hydroxide is titrated with a solution of hydrochloric acid. If 25.0 mL of 0.100 M HCl is required to reach the equivalence point, what is the concentration of the NaOH solution?
A. 0.100 M
B. 0.200 M
C. 0.500 M
D. 1.00 M
Question 11
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 2.5 g of C(s) at 298 K.
A. -981.25 kJ
B. -981.375 kJ
C. -981.5 kJ
D. -981.625 kJ
Question 12
The following diagram shows a titration setup. Identify the subs\tance being titrated.
A. HCl
B. NaOH
C. H2SO4
D. NaCl
Question 13
A 2.5 M solution of HCl is prepared by dissolving 12.5 g of HCl in 1 L of water. Calculate the pH of the solution.
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 14
A metal (M) reacts with chlorine gas to form a white solid. The reaction is highly exothermic, relea\sing 22.5 kJ of heat per mole of M. If 2.5 g of M reacts with 1.5 g of Cl2, what is the percentage yield of the reaction?
A. 75%
B. 80%
C. 85%
D. 90%
Question 15
A 2.00-g sample of a hydrocarbon is combusted in a bomb calorimeter. If the heat of combustion is -1234 kJ, what is the empirical formula of the compound?
A. C2H6
B. C3H8
C. C4H10
D. C5H12

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