POST UTME AAUA 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A solution of sodium chloride (NaCl) is prepared by dissolving 10 g of NaCl in 100 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 1.0 M
C. 10 M
D. 100 M
Question 2
A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. What is the molar mass of the repeating unit?
A. 200 g/mol
B. 400 g/mol
C. 500 g/mol
D. 600 g/mol
Question 3
A 50.0 g sample of a metal is heated in a crucible to produce a 25.0 g sample of a metal oxide. What is the mass of the metal that was lost during the reaction?
A. 12.5 g
B. 25.0 g
C. 37.5 g
D. 50.0 g
Question 4
The energy change associated with the formation of a mole of water vapor at 100°C and 1 atm is -40.7 kJ/mol. Calculate the s\tandard enthalpy of vaporization of water at 100°C.
A. 44.0 kJ/mol
B. 40.7 kJ/mol
C. 45.5 kJ/mol
D. 42.2 kJ/mol
Question 5
A 2.5 L sample of a gas at 27°C and 1 atm is collected over water. If the vapor pressure of water at 27°C is 0.0313 atm, what is the partial pressure of the gas?
A. 0.9687 atm
B. 0.9697 atm
C. 0.971 atm
D. 0.972 atm
Question 6
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen gas (H2) react with excess oxygen gas according to the equation: 2H2 + O2 → 2H2O.
A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 7.5 moles
Question 7
A sample of an ideal gas at 25°C and 1 atm is heated to 100°C while maintaining a cons\tant pressure. What is the ratio of the final volume to the initial volume?
A. 2
B. 4
C. \frac{5}{3}
D. \frac{3}{5}
Question 8
A polymer is prepared by the condensation reaction of ethylene glycol and adipic acid. If 1.5 moles of ethylene glycol react with 1.2 moles of adipic acid, what is the limiting reac\tant?
A. ethylene glycol
B. adipic acid
C. neither
D. both
Question 9
A sample of an ideal gas at 25°C and 1 atm undergoes a process where its volume is reduced to one-third of its initial value. What is the new pressure of the gas, assuming it remains ideal?
A. 1 atm
B. 3 atm
C. 4 atm
D. 6 atm
Question 10
A sample of nitrogen gas (N2) is collected over water at a temperature of 25°C and a pressure of 1.2 atm. What is the partial pressure of the nitrogen gas?
A. 0.9 atm
B. 1.0 atm
C. 1.1 atm
D. 1.2 atm
Question 11
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 12
A polymer has a molecular weight of 100,000 g/mol. If 1.0 g of the polymer is dissolved in 100 mL of solvent, what is the concentration of the solution in g/L?
A. 0.1 g/L
B. 1.0 g/L
C. 10 g/L
D. 100 g/L
Question 13
A solution contains 0.0500 M NaCl. What is the concentration of Cl- ions in the solution?
A. 0.0500 M
B. 0.0500 M
C. 0.100 M
D. 0.0500 M
Question 14
A sample of nitrogen gas at 25°C and 1 atm is heated to 50°C. What is the new volume of the gas, assuming ideal behavior?
A. 2.5 L
B. 1.5 L
C. 1.0 L
D. 0.5 L
Question 15
The reaction of methane with chlorine to form chloromethane is an example of a substitution reaction. What is the product of the reaction?
A. CH_3Cl
B. CH_2Cl_2
C. CHCl_3
D. CCl_4

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