POST UTME JOSEPH AYO BABALOLA UNIVERSITY 2024 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 3.0 M solution of a strong acid HA is mixed with a 3.0 M solution of a strong base BOH. If the initial concentrations of HA and BOH are 3.0 M, and the initial concentrations of H+ and OH- are negligible, what is the pH of the resulting solution after the reaction is complete?
A. 2
B. 3
C. 4
D. 5
Question 2
A 2.5 M solution of sodium hydroxide (NaOH) is prepared by dissolving 12.5 g of NaOH in water to make 1 L of solution. What is the molarity of the solution?
A. 0.25 M
B. 0.3125 M
C. 0.5 M
D. 0.625 M
Question 3
A sample of a non-metallic element has a mass of 2.5 g and a volume of 5.0 mL. If the density of the element is 3.5 g/mL, what is the molar mass of the element?
A. 10
B. 20
C. 30
D. 40
Question 4
A sample of a gas at 25°C and 1 atm is compressed to 2 atm. What is the new volume of the gas?
A. 0.5 L
B. 1 L
C. 2 L
D. 4 L
Question 5
A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. The initial pH of the acid solution is 3. If 20 mL of NaOH is added, the pH of the solution increases to 4.5. What is the number of moles of HA present in 1 L of the initial acid solution?
A. 0.02 mol
B. 0.03 mol
C. 0.04 mol
D. 0.05 mol
Question 6
A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. The initial pH of the acid solution is 3. If 20 mL of NaOH is added, the pH of the solution increases to 4.5. What is the number of moles of HA present in 1 L of the initial acid solution?
A. 0.02 mol
B. 0.03 mol
C. 0.04 mol
D. 0.05 mol
Question 7
A 0.1 M solution of a salt MX is prepared by dissolving 0.1 mol of the salt in 1 L of water. If the pH of the solution is 7, what is the value of pKa of the salt?
A. 7
B. 8
C. 9
D. 10
Question 8
A 10.0 g sample of a metal \( molar mass = 50.0 g/mol \) is dissolved in 100.0 mL of a solution containing 0.100 M HCl. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 9
A solution of 0.1 M HCl is mixed with a solution of 0.1 M NaOH. What is the resulting concentration of HCl?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M
Question 10
The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is initially present, how much of the subs\tance will remain after 10 years?
A. 12.5 g
B. 25 g
C. 50 g
D. 100 g
Question 11
A sample of a metal has a mass of 4.0 g and a volume of 8.0 mL. If the density of the metal is 2.5 g/mL, what is the molar mass of the metal?
A. 20
B. 30
C. 40
D. 50
Question 12
A 1.0 M solution of a weak acid HA is mixed with a 1.0 M solution of a weak base BOH. If the initial concentrations of HA and BOH are 1.0 M, and the initial concentrations of H+ and OH- are negligible, what is the pH of the resulting solution after the reaction is complete?
A. 3
B. 4
C. 5
D. 6
Question 13
The reaction between hydrogen gas and chlorine gas is a classic example of a synthesis reaction. Write the balanced chemical equation for this reaction.
A. H2 + Cl2 → HCl
B. H2 + Cl2 → HCl2
C. H2 + Cl2 → HClO
D. H2 + Cl2 → HClO2
Question 14
A solution of 0.1 M NaOH is mixed with a solution of 0.1 M HCl. What is the pH of the resulting solution?
A. 1
B. 7
C. 10
D. 14
Question 15
A 2.5 L flask contains 0.5 mol of an ideal gas at a temperature of 300 K. If the gas is heated to 400 K, what is the new volume of the gas?
A. 2.5 L
B. 3.33 L
C. 4 L
D. 5 L

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