POST UTME OAU 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 0.1 M solution of K2Cr2O7 is prepared by dissolving 2.5 g of K2Cr2O7 in 100 mL of water. Calculate the number of moles of K2Cr2O7 used in preparing the solution.
A. 0.005 mol
B. 0.01 mol
C. 0.015 mol
D. 0.02 mol
Question 2
A 0.5 M solution of NaOH is prepared by dissolving 2.5 g of NaOH in 1 L of water. What is the molarity of the solution?
A. 0.5 M
B. 1.0 M
C. 2.5 M
D. 5.0 M
Question 3
A sample of nitrogen gas (N2) is heated to 500 K. What is the average kinetic energy of the nitrogen molecules?
A. 1.5 kJ/mol
B. 3.0 kJ/mol
C. 4.5 kJ/mol
D. 6.0 kJ/mol
Question 4
A 5.00 L sample of a gas at 25°C and 1.00 atm is compressed to 10.0 L at the same temperature. What is the new pressure?
A. 2.00 atm
B. 4.00 atm
C. 6.00 atm
D. 8.00 atm
Question 5
A solution contains 0.1 M NaCl and 0.2 M NaNO3. What is the concentration of Cl- ions in the solution?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M
Question 6
A 2 M solution of HCl is prepared by dissolving 40 g of HCl in 100 mL of water. Calculate the pH of the solution.
A. 1
B. 2
C. 3
D. 4
Question 7
A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the solution?
A. 1
B. 2
C. 3
D. 4
Question 8
The half-life of a radioactive subs\tance is 5 days. If 100 mg of the subs\tance is present initially, how much of the subs\tance will remain after 10 days?
A. 12.5 mg
B. 25 mg
C. 50 mg
D. 100 mg
Question 9
Determine the number of moles of electrons transferred during the electrolysis of 2.5 L of water at 25°C and 1 atm, given that the cell potential is 1.23 V and the current is 0.5 A.
A. 0.5 mol
B. 1.0 mol
C. 1.5 mol
D. 2.0 mol
Question 10
The half-life of a radioactive subs\tance is 5 days. If 100 mg of the subs\tance is present initially, how much of the subs\tance will remain after 10 days?
A. 12.5 mg
B. 25 mg
C. 50 mg
D. 100 mg
Question 11
The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of C(s) to form CO(g).
A. 110.5 kJ/mol
B. -110.5 kJ/mol
C. 0 kJ/mol
D. -1.5 kJ/mol
Question 12
What is the major product of the reaction between 2-methylpropane and HCl?
A. 2-chloro-2-methylpropane
B. 2-methyl-2-chloropropane
C. 2-chloro-1-methylpropane
D. 2-methyl-1-chloropropane
Question 13
A 2 M solution of HCl is prepared by dissolving 40 g of HCl in 100 mL of water. Calculate the pH of the solution.
A. 1
B. 2
C. 3
D. 4
Question 14
A 2.50 g sample of sulfur (S8) is burned in oxygen to produce sulfur dioxide (SO2). If the reaction is 95% efficient, what is the volume of SO2 produced at STP?
A. 1.25 L
B. 2.50 L
C. 3.75 L
D. 5.00 L
Question 15
A 3.0 M solution of HCl is prepared by dissolving 6.0 g of HCl in 1 L of water. What is the molarity of the solution?
A. 3.0 M
B. 6.0 M
C. 9.0 M
D. 12.0 M

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