POST UTME KSU 2020 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 5.00 g sample of a metal is heated in a crucible until it is completely oxidized. The mass of the oxide formed is 7.50 g. Calculate the percentage of the metal that is oxidized.
A. 50.0%
B. 60.0%
C. 70.0%
D. 80.0%
Question 2
A metal (M) reacts with oxygen gas to form a white solid. The reaction is as follows: 4M + 3O2 → 2M2O3. If 2.50 g of M2O3 is formed from 1.50 g of M, what is the molar mass of M?
A. 50.0 g/mol
B. 75.0 g/mol
C. 100 g/mol
D. 150 g/mol
Question 3
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen gas (H2) react with oxygen gas according to the equation: 2H2 + O2 → 2H2O.
A. 1.25 mol
B. 2.5 mol
C. 5.0 mol
D. 7.5 mol
Question 4
A 2.5 M solution of NaOH is titrated with 0.5 M HCl. What is the pH of the solution after 25 mL of HCl has been added?
A. 9
B. 10
C. 11
D. 12
Question 5
The diagram below shows a titration setup. What is the purpose of the burette?
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 s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.
A. -110.5 kJ/mol
B. -110.5 kJ/mol
C. -110.5 kJ/mol
D. -110.5 kJ/mol
Question 7
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 1000 mL of water. What is the concentration of Na+ ions in the solution?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.5 M
Question 8
A certain metal (M) reacts with chlorine gas (Cl2) to form a metal chloride (MCl2). If 2.0 g of the metal chloride is obtained from 3.2 g of the metal, calculate the percentage yield of the metal chloride.
A. 60%
B. 70%
C. 80%
D. 90%
Question 9
The reaction between sulfuric acid (H2SO4) and sodium hydroxide (NaOH) produces sodium sulfate (Na2SO4) and water (H2O). The balanced chemical equation for this reaction is: H2SO4 + 2NaOH → Na2SO4 + 2H2O. If 2.0 moles of H2SO4 react with excess NaOH, what is the limiting reac\tant?
A. H2SO4
B. NaOH
C. Na2SO4
D. H2O
Question 10
The compound benzene (C6H6) is a hydrocarbon with the molecular formula C6H6. What is the IUPAC name of this compound?
A. Benzene
B. Toluene
C. Xylene
D. Ethylbenzene
Question 11
A 0.1 M solution of NaOH is prepared by dissolving 4.0 g of NaOH in 1000 mL of water. What is the pH of the solution?
A. 13
B. 14
C. 15
D. 16
Question 12
A sample of air is collected over water and found to have a partial pressure of 0.1 atm. What is the mole \fraction of the gas in the air?
A. 0.1
B. 0.2
C. 0.3
D. 0.4
Question 13
A metal has a density of 7.5 g/cm^3 and a molar mass of 40 g/mol. What is the volume of 3 moles of the metal?
A. 0.75 cm^3
B. 0.75 cm^3
C. 0.75 cm^3
D. 0.75 cm^3
Question 14
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 15
A 2.00 M solution of H2SO4 is titrated with 1.00 M NaOH. What is the pH of the solution after 20.0 mL of NaOH has been added?
A. 1.00
B. 2.00
C. 3.00
D. 4.00

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