POST UTME UNN 2019 Chemistry | Objective

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Question 1 View Details
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the initial pH of the HCl solution is 1.00, what is the pH of the solution after the addition of 25.0 mL of NaOH?
A. 2.00
Correct B. 3.00
C. 4.00
D. 5.00

Correct Answer: B

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Question 2 View Details
A reaction is represented by the equation: \( 2A + B \rightarrow 2C + D \). If the rate cons\tant for the reaction is 0.0500 s\( ^{-1} \) and the initial concentrations of A and B are 0.100 M and 0.0500 M, respectively, what is the concentration of A after 10.0 s?
A. 0.0500 M
Correct B. 0.0750 M
C. 0.100 M
D. 0.125 M

Correct Answer: B

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Question 3 View Details
A diagram of a titration setup is shown below. If the burette contains 0.100 M HCl and the initial pH of the solution is 3.00, what is the pH of the solution after the addition of 25.0 mL of HCl?
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 4 View Details
A 25.0 mL sample of 0.100 M NaOH is titrated with 0.100 M HCl. If the initial pH of the NaOH solution is 12.00, what is the pH of the solution after the addition of 25.0 mL of HCl?
A. 7.00
B. 8.00
C. 9.00
Correct D. 10.00

Correct Answer: D

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Question 5 View Details
A reaction is represented by the equation: \( A \rightarrow 2B + C \). If the rate cons\tant for the reaction is 0.0500 s\( ^{-1} \) and the initial concentration of A is 0.100 M, what is the concentration of B after 10.0 s?
A. 0.0500 M
Correct B. 0.0750 M
C. 0.100 M
D. 0.125 M

Correct Answer: B

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Question 6 View Details
A 2.50 g sample of a non-metallic oxide of nitrogen is decomposed by heating with graphite. The volume of nitrogen gas produced at 25°C and 1 atm is 2.50 L. Calculate the molar mass of the oxide.
A. 60 g/mol
B. 80 g/mol
Correct C. 100 g/mol
D. 120 g/mol

Correct Answer: C

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Question 7 View Details
The half-life of a radioactive subs\tance is 5.0 days. If 100 mg of the subs\tance is present initially, how much will remain after 20 days?
Correct A. 12.5 mg
B. 25 mg
C. 50 mg
D. 100 mg

Correct Answer: A

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Question 8 View Details
A solution of 0.10 M HCl is titrated with 0.10 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the volume of HCl required to reach the equivalence point?
Correct A. 25 mL
B. 50 mL
C. 100 mL
D. 200 mL

Correct Answer: A

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Question 9 View Details
A 2.0 L flask contains 1.0 M H2SO4. If 0.10 M NaOH is added to the flask, what is the concentration of the resulting solution?
A. 0.50 M
B. 0.75 M
Correct C. 1.0 M
D. 1.25 M

Correct Answer: C

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Question 10 View Details
A 2.0 g sample of a hydrocarbon is burned in a combustion apparatus. The volume of CO2 produced is 2.5 L at 25°C and 1 atm. What is the empirical formula of the hydrocarbon?
Correct A. C2H4
B. C3H6
C. C4H8
D. C5H10

Correct Answer: A

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Question 11 View Details
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after the addition of 25.0 mL of NaOH.
A. 2.00
B. 3.00
Correct C. 4.00
D. 5.00

Correct Answer: C

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Question 12 View Details
The reaction between H2S and O2 is catalyzed by a metal ion. Which of the following metal ions is most likely to be the catalyst?
A. Cu2+
B. Fe3+
Correct C. Mn2+
D. Cr3+

Correct Answer: C

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Question 13 View Details
A 2.00 g sample of a non-metallic oxide is dissolved in water to form a solution with a pH of 7.00. What is the molar mass of the oxide?
A. 50.0 g/mol
Correct B. 100 g/mol
C. 150 g/mol
D. 200 g/mol

Correct Answer: B

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Question 14 View Details
A 1.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. What is the partial pressure of the gas?
A. 0.950 atm
B. 0.975 atm
Correct C. 1.00 atm
D. 1.05 atm

Correct Answer: C

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Question 15 View Details
A 2.00 g sample of a metal is dissolved in acid to form a solution with a concentration of 0.100 M. What is the molar mass of the metal?
A. 50.0 g/mol
Correct B. 100 g/mol
C. 150 g/mol
D. 200 g/mol

Correct Answer: B

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Question 16 View Details
Determine the pH of a 0.1 M solution of HCl after 10 mL of 0.1 M NaOH has been added to 50 mL of the HCl solution. Assume that the volume of the solution remains cons\tant at 60 mL.
A. 1.0
Correct B. 2.0
C. 3.0
D. 4.0

Correct Answer: B

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Question 17 View Details
A 25 mL sample of 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the number of moles of HCl that have reacted after 15 mL of NaOH has been added.
A. 0.0025
Correct B. 0.0050
C. 0.0075
D. 0.0100

Correct Answer: B

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Question 18 View Details
The reaction between HCl and NaOH is represented by the equation: HCl + NaOH → NaCl + H2O. If 50 mL of 0.1 M HCl is mixed with 50 mL of 0.1 M NaOH, what is the concentration of the resulting solution?
A. 0.05 M
Correct B. 0.10 M
C. 0.15 M
D. 0.20 M

Correct Answer: B

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Question 19 View Details
A solution containing 0.1 M HCl and 0.1 M NaOH is prepared by mixing equal volumes of each solution. What is the pH of this solution?
A. 1.0
Correct B. 2.0
C. 3.0
D. 4.0

Correct Answer: B

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Question 20 View Details
A 25 mL sample of 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the number of moles of NaOH that have reacted after 15 mL of NaOH has been added.
A. 0.0025
Correct B. 0.0050
C. 0.0075
D. 0.0100

Correct Answer: B

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Question 21 View Details
A sample of an ideal gas is heated at cons\tant volume. Which of the following statements is true?
A. The pressure of the gas increases.
B. The pressure of the gas decreases.
Correct C. The pressure of the gas remains cons\tant.
D. The pressure of the gas becomes zero.

Correct Answer: C

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Question 22 View Details
A solution of 2.5 g of NaCl in 50 g of water is prepared. What is the molality of the solution?
A. 0.1 m
Correct B. 0.2 m
C. 0.3 m
D. 0.4 m

Correct Answer: B

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Question 23 View Details
The s\tandard electrode potential of the couple Zn2+/Zn is -0.76 V. What is the s\tandard electrode potential of the couple Cu2+/Cu?
A. -0.34 V
Correct B. -0.44 V
C. -0.54 V
D. -0.64 V

Correct Answer: B

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Question 24 View Details
A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in water to make 1.0 L of solution. What is the pH of the solution?
A. 1.0
Correct B. 2.0
C. 3.0
D. 4.0

Correct Answer: B

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Question 25 View Details
A sample of a gas occupies a volume of 2.5 L at a pressure of 1.0 atm and a temperature of 298 K. What is the volume of the gas at a pressure of 2.0 atm and a temperature of 298 K?
A. 1.25 L
B. 2.5 L
Correct C. 3.75 L
D. 5.0 L

Correct Answer: C

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