POST UTME EKSU 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the number of moles of ΔHgS that can be formed from 0.500 mol of Hg(NO3)2 and 0.750 mol of Na2S, given that the reaction is: Hg(NO3)2 + Na2S → ΔHgS + 2NaNO3.
A. 0.250 mol
B. 0.375 mol
C. 0.500 mol
D. 0.750 mol
Question 2
A diagram of a chromatography setup is shown below. What is the purpose of the stationary phase in this setup?
A. To separate the components of the mixture
B. To identify the components of the mixture
C. To measure the concentration of the components
D. To purify the components of the mixture
Question 3
A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. If the density of the solution is 1.00 g/mL, what is the molar mass of the polymer?
A. 100.0 g/mol
B. 200.0 g/mol
C. 300.0 g/mol
D. 400.0 g/mol
Question 4
A 0.500 L sample of a 0.100 M solution of NaOH is mixed with a 0.500 L sample of a 0.100 M solution of HCl. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 5
A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?
A. To measure the volume of the titrant
B. To measure the volume of the analyte
C. To mix the titrant and analyte
D. To separate the titrant and analyte
Question 6
The rate cons\tant (k) of a first-order reaction is given by the equation: k = 2.303/t \log10\( A0/A \). If the half-life of the reaction is 10 minutes, what is the value of k?
A. 0.0693 min^-1
B. 0.693 min^-1
C. 1.386 min^-1
D. 2.303 min^-1
Question 7
A sample of 1.0 g of a non-metallic element has a density of 5.0 g/cm³. What is the volume of the sample in cm³?
A. 0.2 cm³
B. 0.5 cm³
C. 1.0 cm³
D. 2.0 cm³
Question 8
A 2.0 M solution of HCl is prepared by dissolving 40 g of HCl in 100 mL of water. What is the concentration of the solution in mol/L?
A. 0.4 mol/L
B. 1.0 mol/L
C. 2.0 mol/L
D. 4.0 mol/L
Question 9
A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in 100 mL of water. What is the pH of the solution?
A. 0.5
B. 1.0
C. 2.0
D. 3.0
Question 10
A 2.50 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 torr, what is the partial pressure of the gas?
A. 0.980 atm
B. 0.990 atm
C. 1.00 atm
D. 1.01 atm
Question 11
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol?
A. -285.8 kJ/mol
B. -285.9 kJ/mol
C. -286.0 kJ/mol
D. -286.1 kJ/mol
Question 12
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of the solution in g/L?
A. 0.6 g/L
B. 6.0 g/L
C. 60 g/L
D. 600 g/L
Question 13
A 0.1 M solution of NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of Cl^- ions in the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 14
A sample of an ideal gas is heated at cons\tant volume. Which of the following statements is true about the change in entropy of the gas?
A. The entropy of the gas increases.
B. The entropy of the gas decreases.
C. The entropy of the gas remains cons\tant.
D. The entropy of the gas becomes undefined.
Question 15
A 2.0 L flask contains 1.0 atm of He gas at 298 K. What is the pressure of the gas in the flask if it is heated to 373 K?
A. 1.5 atm
B. 2.0 atm
C. 2.5 atm
D. 3.0 atm

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