POST UTME UNILORIN 2024 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The pH of a 0.100 M solution of a weak acid HA is 4.25. What is the value of Ka for the acid?
A. 1.3 x 10^\( -5 \)
B. 1.3 x 10^\( -4 \)
C. 1.3 x 10^\( -3 \)
D. 1.3 x 10^\( -2 \)
Question 2
The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 25.0 mL of 0.100 M CuSO4(aq) is mixed with 25.0 mL of 0.100 M Zn(NO3)2(aq), what is the limiting reac\tant?
A. Zn(s)
B. CuSO4(aq)
C. Zn(NO3)2(aq)
D. Neither Zn(s) nor CuSO4(aq) is the limiting reac\tant.
Question 3
A sample of Fe2O3 is heated in a Bunsen burner flame. What is the resulting product?
A. Fe
B. FeO
C. Fe2O3
D. Fe3O4
Question 4
A 25.0 mL sample of a 0.100 M solution of NaOH is titrated with a 0.100 M solution of HCl. What is the pH of the solution after the titration is complete?
A. 7.00
B. 7.25
C. 7.50
D. 7.75
Question 5
A 2.00-g sample of a non-metallic element is heated in a crucible until it sublimes. If the temperature of the crucible is 250°C, and the vapor pressure of the element at this temperature is 1.00 atm, determine the molar mass of the element.
A. \( M = 16.0 , \text{g/mol} \)
B. \( M = 32.0 , \text{g/mol} \)
C. \( M = 48.0 , \text{g/mol} \)
D. \( M = 64.0 , \text{g/mol} \)
Question 6
A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?
A. CH2O
B. C2H4O
C. C3H6O
D. C4H8O
Question 7
The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 25.0 mL of 0.100 M CuSO4(aq) is mixed with 25.0 mL of 0.100 M Zn(NO3)2(aq), what is the limiting reac\tant?
A. Zn(s)
B. CuSO4(aq)
C. Zn(NO3)2(aq)
D. Neither Zn(s) nor CuSO4(aq) is the limiting reac\tant.
Question 8
A sample of CO2 gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of water vapor is 0.02 atm, what is the mole \fraction of CO2 in the gas mixture?
A. 0.98
B. 0.99
C. 0.995
D. 0.999
Question 9
A 2.0 L flask contains 1.0 mol of O2 gas at a temperature of 298 K. If the gas is allowed to expand to a volume of 5.0 L, what is the new pressure of the gas?
A. 0.20 atm
B. 0.40 atm
C. 0.60 atm
D. 0.80 atm
Question 10
The pH of a 0.100 M solution of a weak acid HA is 4.25. What is the value of Ka for the acid?
A. 1.3 x 10^\( -5 \)
B. 1.3 x 10^\( -4 \)
C. 1.3 x 10^\( -3 \)
D. 1.3 x 10^\( -2 \)
Question 11
A 0.50 M solution of HCl is mixed with a 0.50 M solution of NaOH. If the reaction is allowed to go to completion, what is the pH of the resulting solution?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 12
A 0.50 M solution of AgNO3 is mixed with a 0.50 M solution of NaCl. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?
A. 0.25 M
B. 0.50 M
C. 1.00 M
D. 1.25 M
Question 13
A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?
A. CH2O
B. C2H4O
C. C3H6O
D. C4H8O
Question 14
A solution containing 0.10 M NH3 and 0.20 M HCl is titrated with 0.10 M NaOH. Determine the pH of the solution after 25.0 mL of NaOH has been added.
A. \( \text{pH} = 9.25 \)
B. \( \text{pH} = 9.50 \)
C. \( \text{pH} = 9.75 \)
D. \( \text{pH} = 10.00 \)
Question 15
A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?
A. CH2O
B. C2H4O
C. C3H6O
D. C4H8O

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