POST UTME JOSEPH AYO BABALOLA UNIVERSITY 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The s\tandard enthalpy of formation of water (H2O) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1.00 mol of hydrogen gas (H2) to form H2O.
A. -285.8
B. -286.8
C. -287.8
D. -288.8
Question 2
A 2.00 M solution of HCl is titrated with 1.00 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the concentration of HCl?
A. 0.500 M
B. 1.00 M
C. 2.00 M
D. 4.00 M
Question 3
A 10.0 g sample of a metal is heated in a Bunsen burner flame. If the metal is 80.0% pure, what is the mass of the impurities present?
A. 2.00 g
B. 4.00 g
C. 6.00 g
D. 8.00 g
Question 4
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 15.0 mL of NaOH has been added.
A. 2.00
B. 3.00
C. 4.00
D. 5.00
Question 5
A 2.00 M solution of HCl is titrated with 0.500 M NaOH. If 30.0 mL of NaOH is required to reach the equivalence point, what is the volume of HCl in liters?
A. 60.0 mL
B. 75.0 mL
C. 90.0 mL
D. 120 mL
Question 6
The half-life of a radioactive subs\tance is 5.00 days. If 100.0 mg of the subs\tance is initially present, what is the amount remaining after 20.0 days?
A. 10.0 mg
B. 20.0 mg
C. 30.0 mg
D. 40.0 mg
Question 7
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. If 2.50 mol of CO2 is produced at 298 K, what is the total enthalpy change for the reaction?
A. -987.5 kJ
B. -393.5 kJ
C. 393.5 kJ
D. 987.5 kJ
Question 8
The atomic number of an element is 20. What is the number of protons in the nucleus of an atom of this element?
A. 18
B. 20
C. 22
D. 24
Question 9
The diagram below shows a titration curve for the reaction between HCl and NaOH.
A. The reaction is exothermic.
B. The reaction is \endothermic.
C. The reaction is neutral.
D. The reaction is acidic.
Question 10
The ideal gas law is given by PV = nRT. What is the unit of the gas cons\tant R?
A. J/mol·K
B. Pa·m³/mol·K
C. kg/mol·K
D. m³/mol·K
Question 11
A sample of nitrogen gas is collected over water at 25°C and 1.00 atm. If the partial pressure of water vapor is 0.031 atm, calculate the total pressure of the gas.
A. 1.00 atm
B. 1.03 atm
C. 1.05 atm
D. 1.07 atm
Question 12
At 25°C, the equilibrium cons\tant (Kp) for the reaction N2(g) + 3H2(g) ⇌ 2NH3(g) is 0.065. Calculate the partial pressure of NH3(g) when the partial pressures of N2(g) and H2(g) are 0.50 atm and 1.00 atm, respectively.
A. 0.025 atm
B. 0.050 atm
C. 0.100 atm
D. 0.200 atm
Question 13
The diagram below shows a chemical apparatus setup. Identify the subs\tance being titrated.
A. HCl
B. NaOH
C. H_2SO_4
D. Na_2CO_3
Question 14
A sample of gas occupies a volume of 2.5 L at a pressure of 1.5 atm. What is the pressure of the gas if the volume is reduced to 1.2 L?
A. 2.1 atm
B. 2.5 atm
C. 3.0 atm
D. 3.5 atm
Question 15
The reaction of nitrogen dioxide with water is highly exothermic. Write the balanced chemical equation for this reaction, including the s\tandard enthalpy change (ΔH°) in kJ/mol.
A. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{NO}
B. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{NO}_3 + \text{NO}
C. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{O}_2 + \text{NO}_2
D. \text{N}_2\text{O}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{O}_2 + \text{NO}_2

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