POST UTME LASU 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 g sample of a polymer is dissolved in 100 mL of a solvent. The solution has a vis\cosity of 1.2 Pa·s. Calculate the molar mass of the polymer.
A. 10^5 g/mol
B. 10^6 g/mol
C. 10^7 g/mol
D. 10^8 g/mol
Question 2
A 25 mL sample of a solution containing 0.1 M NaOH is titrated with 0.1 M HCl. Calculate the number of moles of HCl required to reach the equivalence point.
A. 0.0025 mol
B. 0.0050 mol
C. 0.0075 mol
D. 0.0100 mol
Question 3
A 0.1 M solution of H2SO4 is mixed with a 0.1 M solution of NaOH. Calculate the pH of the resulting solution.
A. 1
B. 2
C. 3
D. 4
Question 4
The diagram below shows a titration setup. Identify the part labeled A.
A. Burette
B. Conical Flask
C. Pipette
D. Thermometer
Question 5
The diagram below shows a titration setup. What is the concentration of the NaOH(aq) solution used in the titration?
A. 0.100 M
B. 0.500 M
C. 1.00 M
D. 2.00 M
Question 6
A sample of nitrogen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. Calculate the partial pressure of nitrogen gas in the sample.
A. 0.95 atm
B. 0.99 atm
C. 1.00 atm
D. 1.05 atm
Question 7
The diagram below shows a titration setup.
A. The burette contains the acid.
B. The beaker contains the acid.
C. The burette contains the base.
D. The beaker contains the base.
Question 8
A metal M reacts with oxygen gas to form a white solid MO. If the molar mass of M is 40 g/mol and the molar mass of MO is 80 g/mol, what is the molar mass of O?
A. 40 g/mol
B. 60 g/mol
C. 80 g/mol
D. 100 g/mol
Question 9
Determine the pH of a 0.1 M solution of HCl in water at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \).
A. 1
B. 2
C. 3
D. 4
Question 10
A sample of a polymer has a molecular weight of 50,000 g/mol. If the polymer has a degree of polymerization of 500, what is the molar mass of the monomer?
A. 100 g/mol
B. 200 g/mol
C. 300 g/mol
D. 400 g/mol
Question 11
A 1.00 M solution of HCl(aq) is mixed with 1.00 M solution of NaOH(aq). If the reaction is carried out in a calorimeter, and the temperature of the solution increases by 2.50°C, what is the value of ΔH for the reaction?
A. -54.0 kJ/mol
B. -45.0 kJ/mol
C. -36.0 kJ/mol
D. -27.0 kJ/mol
Question 12
The atomic radius of a certain element is 100 pm. If the element has an atomic number of 12, what is its electron configuration?
A. 1s² 2s² 2p⁶ 3s²
B. 1s² 2s² 2p⁶ 3s² 3p⁶
C. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
D. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶
Question 13
A 1.0 M solution of a non-electrolyte solute is prepared by dissolving 18 g of the solute in 1.0 L of water. What is the molar mass of the solute?
A. 18 g/mol
B. 20 g/mol
C. 22 g/mol
D. 24 g/mol
Question 14
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.5 atm
B. 2.0 atm
C. 2.5 atm
D. 3.0 atm
Question 15
A 2.5 L flask contains 0.5 mol of N2 and 0.5 mol of O2 at 25°C. Calculate the partial pressure of O2 in the flask.
A. 0.5 atm
B. 1.0 atm
C. 1.5 atm
D. 2.0 atm

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