POST UTME AAUA 2023 Chemistry | Objective

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Question 1 View Details
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.
Correct A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 7.5 moles

Correct Answer: A

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Question 2 View Details
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?
Correct A. 0.9687 atm
B. 0.9697 atm
C. 0.971 atm
D. 0.972 atm

Correct Answer: A

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Question 3 View Details
A solution contains 0.0500 M NaCl. What is the concentration of Cl- ions in the solution?
Correct A. 0.0500 M
B. 0.0500 M
C. 0.100 M
D. 0.0500 M

Correct Answer: A

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Question 4 View Details
A 25.0 mL sample of a solution containing 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the solution after the titration?
A. 1.00
Correct B. 2.00
C. 3.00
D. 4.00

Correct Answer: B

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Question 5 View Details
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?
Correct A. 0.9687 atm
B. 0.9697 atm
C. 0.971 atm
D. 0.972 atm

Correct Answer: A

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Question 6 View Details
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
Correct C. 5.0 moles
D. 10.0 moles

Correct Answer: C

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Question 7 View Details
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
Correct B. adipic acid
C. neither
D. both

Correct Answer: B

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Question 8 View Details
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
Correct D. Rb

Correct Answer: D

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Question 9 View Details
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
Correct B. 1.0 atm
C. 1.1 atm
D. 1.2 atm

Correct Answer: B

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Question 10 View Details
A solution of sodium chloride (NaCl) is prepared by dissolving 35.5 g of NaCl in 250 mL of water. What is the molarity of the solution?
A. 0.1 M
B. 0.2 M
Correct C. 0.3 M
D. 0.4 M

Correct Answer: C

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Question 11 View Details
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
Correct B. 3 atm
C. 4 atm
D. 6 atm

Correct Answer: B

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Question 12 View Details
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
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 13 View Details
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
Correct B. 1.5 atm
C. 2 atm
D. 2.5 atm

Correct Answer: B

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Question 14 View Details
A polymer chain 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. 100 g/mol
B. 200 g/mol
Correct C. 500 g/mol
D. 1000 g/mol

Correct Answer: C

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Question 15 View Details
A sample of sulfur dioxide gas is collected over water at 25°C and 1 atm. What is the partial pressure of the sulfur dioxide gas?
A. 0.9 atm
Correct B. 1 atm
C. 1.1 atm
D. 1.2 atm

Correct Answer: B

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Question 16 View Details
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?
Correct A. 2.5 L
B. 1.5 L
C. 1.0 L
D. 0.5 L

Correct Answer: A

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Question 17 View Details
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
Correct B. 1.0 g/L
C. 10 g/L
D. 100 g/L

Correct Answer: B

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Question 18 View Details
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
Correct B. 1.0 M
C. 10 M
D. 100 M

Correct Answer: B

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Question 19 View Details
A sample of sulfur dioxide gas (SO2) is collected over water at a temperature of 20°C and a pressure of 1 atm. What is the partial pressure of the SO2 gas?
A. 0.5 atm
Correct B. 1.0 atm
C. 1.5 atm
D. 2.0 atm

Correct Answer: B

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Question 20 View Details
A diagram of a titration setup is shown below. What is the purpose of the burette in this experiment?
Correct 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

Correct Answer: A

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Question 21 View Details
The reaction of sulfur dioxide with oxygen to form sulfur trioxide is an example of a redox reaction. What is the oxidation state of sulfur in sulfur trioxide?
A. 0
B. +2
C. +4
Correct D. +6

Correct Answer: D

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Question 22 View Details
A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. What is the pressure of the gas?
A. 1.01 x 10^5 Pa
Correct B. 2.02 x 10^5 Pa
C. 3.03 x 10^5 Pa
D. 4.04 x 10^5 Pa

Correct Answer: B

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Question 23 View Details
The diagram below shows a titration setup.
A. The burette contains the acid.
B. The beaker contains the acid.
Correct C. The burette contains the base.
D. The beaker contains the base.

Correct Answer: C

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Question 24 View Details
The reaction of methane with chlorine to form chloromethane is an example of a substitution reaction. What is the product of the reaction?
Correct A. CH_3Cl
B. CH_2Cl_2
C. CHCl_3
D. CCl_4

Correct Answer: A

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Question 25 View Details
The diagram below shows a graph of the concentration of a solution against time.
Correct A. The concentration of the solution is increa\sing.
B. The concentration of the solution is decrea\sing.
C. The concentration of the solution is cons\tant.
D. The concentration of the solution is zero.

Correct Answer: A

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