POST UTME LASU 2024 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The boiling point of a subs\tance is the temperature at which the vapor pressure of the subs\tance equals the surrounding pressure. What is the boiling point of water at s\tandard atmospheric pressure?
A. 373.15 K
B. 373.15 °C
C. 100 °C
D. 100 K
Question 2
A 0.5 M solution of a weak acid HA has a pH of 4.5. Calculate the value of Ka.
A. 1.0 x 10^\( -5 \)
B. 1.0 x 10^\( -4 \)
C. 1.0 x 10^\( -3 \)
D. 1.0 x 10^\( -2 \)
Question 3
A 2.00 M solution of HCl is prepared by dissolving 40.0 g of HCl in enough water to make 1.00 L of solution. What is the concentration of H+ ions in the solution?
A. 1.00 M
B. 2.00 M
C. 4.00 M
D. 8.00 M
Question 4
A 2.0 M solution of a weak base B has a pOH of 10.5. Calculate the value of Kb.
A. 1.0 x 10^\( -5 \)
B. 1.0 x 10^\( -4 \)
C. 1.0 x 10^\( -3 \)
D. 1.0 x 10^\( -2 \)
Question 5
A sample of a gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 298 K. What is the new volume of the gas at a pressure of 3.0 atm and a temperature of 323 K?
A. 3.2 L
B. 3.5 L
C. 3.8 L
D. 4.0 L
Question 6
The s\tandard Gibbs free energy of formation of a subs\tance is a measure of the energy change that occurs when one mole of the subs\tance is formed from its constituent elements in their s\tandard states. What is the s\tandard Gibbs free energy of formation of carbon dioxide?
A. -394.4 kJ/mol
B. -393.5 kJ/mol
C. 394.4 kJ/mol
D. 393.5 kJ/mol
Question 7
A 10.0 g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution has a vis\cosity of 0.50 Pa·s. Calculate the molar mass of the polymer.
A. 1000 g/mol
B. 5000 g/mol
C. 10000 g/mol
D. 20000 g/mol
Question 8
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of methane (CH4(g)) at 298 K.
A. -890.3 kJ/mol
B. -890.6 kJ/mol
C. -890.9 kJ/mol
D. -891.1 kJ/mol
Question 9
A 0.5 M solution of a weak acid HA has a pH of 4.5. Calculate the value of Ka.
A. 1.0 x 10^\( -5 \)
B. 1.0 x 10^\( -4 \)
C. 1.0 x 10^\( -3 \)
D. 1.0 x 10^\( -2 \)
Question 10
A sample of a hydrocarbon has a molecular formula of C5H12. What is the type of hydrocarbon?
A. Alkane
B. Alkene
C. Alkyne
D. Aromatic hydrocarbon
Question 11
A 0.500 M solution of NaCl is prepared by dissolving 25.0 g of NaCl in enough water to make 1.00 L of solution. What is the concentration of Cl- ions in the solution?
A. 0.250 M
B. 0.500 M
C. 0.750 M
D. 1.00 M
Question 12
The half-life of a radioactive subs\tance is 10 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 20 years?
A. 25 g
B. 50 g
C. 75 g
D. 100 g
Question 13
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 25.0 mL of NaOH.
A. 2.00
B. 3.00
C. 4.00
D. 5.00
Question 14
The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. What is the s\tandard enthalpy of formation of H2(g)?
A. -285.8 kJ/mol
B. 0 kJ/mol
C. 285.8 kJ/mol
D. 572.8 kJ/mol
Question 15
The boiling point of a subs\tance is the temperature at which the vapor pressure of the subs\tance equals the surrounding pressure. What is the boiling point of water at s\tandard pressure?
A. 100°C
B. 50°C
C. 200°C
D. 300°C

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