POST UTME AAUA 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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 2
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 3
A 2.5 g sample of a metal hydroxide is dissolved in 50 cm3 of water. The resulting solution is found to have a pH of 10.5. What is the molar concentration of the metal hydroxide?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 4
A sample of a metal carbonate is heated strongly. The gas evolved is passed through a solution of calcium chloride. The resulting solution is found to be slightly acidic. What is the name of the gas evolved during the heating of the metal carbonate?
A. Carbon dioxide
B. Nitrogen
C. Oxygen
D. Hydrogen
Question 5
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 6
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 balanced equation: 2H2 + O2 → 2H2O.
A. 1.25 moles
B. 2.5 moles
C. 5.0 moles
D. 10.0 moles
Question 7
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 8
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 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 at 300 K and 2 atm is mixed with an equal volume of oxygen gas at 300 K and 2 atm. What is the partial pressure of nitrogen in the resulting mixture?
A. 1 atm
B. 1.5 atm
C. 2 atm
D. 2.5 atm
Question 11
A 3.0 g sample of a metal carbonate is heated strongly. The gas evolved is passed through a solution of calcium chloride. The resulting solution is found to be slightly acidic. What is the molar mass of the metal carbonate?
A. 100 g/mol
B. 150 g/mol
C. 200 g/mol
D. 250 g/mol
Question 12
The atomic radius of an element increases down a group in the periodic table. Which of the following elements has the largest atomic radius?
A. Li
B. Na
C. K
D. Rb
Question 13
A 3.5 g sample of a metal carbonate is heated strongly. The gas evolved is passed through a solution of calcium chloride. The resulting solution is found to be slightly acidic. What is the molar mass of the metal carbonate?
A. 100 g/mol
B. 150 g/mol
C. 200 g/mol
D. 250 g/mol
Question 14
A 1.00 M solution of HCl is mixed with a 1.00 M solution of NaOH. What is the concentration of the resulting solution?
A. 0.500 M
B. 1.00 M
C. 1.50 M
D. 2.00 M
Question 15
A 2.50 g sample of a metal carbonate is heated to produce a metal oxide. If the mass of the metal oxide is 1.75 g, what is the percentage yield of the reaction?
A. 70%
B. 80%
C. 90%
D. 95%

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