POST UTME ABU 2020 Chemistry | Objective

Are you preparing for POST UTME ABU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2020 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
A 2.50 g sample of a non-volatile solute is dissolved in 25.0 cm³ of water at 25°C. Calculate the molality of the solution.
A. 0.100 m
B. 0.200 m
Correct C. 0.500 m
D. 1.00 m

Correct Answer: C

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Question 2
The pH of a 0.10 M solution of a weak acid HA is 4.25. Calculate the value of Ka for the acid.
A. 1.0 x 10^\( -4 \)
Correct B. 1.0 x 10^\( -5 \)
C. 1.0 x 10^\( -6 \)
D. 1.0 x 10^\( -7 \)

Correct Answer: B

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Question 3
A 2.50 g sample of a non-volatile solute is dissolved in 25.0 cm³ of water at 25°C. Calculate the molality of the solution.
A. 0.100 m
B. 0.200 m
Correct C. 0.500 m
D. 1.00 m

Correct Answer: C

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Question 4
The pH of a 0.10 M solution of a weak acid HA is 4.25. Calculate the value of Ka for the acid.
A. 1.0 x 10^\( -4 \)
Correct B. 1.0 x 10^\( -5 \)
C. 1.0 x 10^\( -6 \)
D. 1.0 x 10^\( -7 \)

Correct Answer: B

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Question 5
A 2.50 g sample of a non-volatile solute is dissolved in 25.0 cm³ of water at 25°C. Calculate the molality of the solution.
A. 0.100 m
B. 0.200 m
Correct C. 0.500 m
D. 1.00 m

Correct Answer: C

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Question 6
Determine the pH of a 0.1 M solution of acetic acid (CH3COOH) at 25°C. The dissociation cons\tant (Ka) of acetic acid is 1.8 × 10^\( -5 \).
A. 2.9
Correct B. 3.9
C. 4.9
D. 5.9

Correct Answer: B

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Question 7
A sample of polystyrene (PS) has a density of 1.05 g/cm3. If 25.0 g of PS is dissolved in 100.0 mL of chloroform, calculate the molar concentration of the polymer.
A. 0.25 M
Correct B. 0.50 M
C. 0.75 M
D. 1.00 M

Correct Answer: B

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Question 8
A 2.50 L flask contains 0.500 mol of an unknown gas at 25°C. Calculate the partial pressure of the gas u\sing the ideal gas law.
A. 0.500 atm
B. 0.750 atm
Correct C. 1.00 atm
D. 1.25 atm

Correct Answer: C

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Question 9
A 0.100 M solution of sodium hydroxide (NaOH) is titrated with 0.100 M hydrochloric acid (HCl). Calculate the pH of the solution after 25.0 mL of HCl has been added.
A. 2.0
Correct B. 3.0
C. 4.0
D. 5.0

Correct Answer: B

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Question 10
A sample of glu\cose (C6H12O6) has a mass of 25.0 g. Calculate the number of moles of glu\cose present.
A. 0.500 mol
B. 0.750 mol
Correct C. 1.00 mol
D. 1.25 mol

Correct Answer: C

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Question 11
Determine the pH of a 0.1 M solution of HCl at 25°C.
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 12
A 25 mL sample of 0.5 M H2SO4 is titrated with 1 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.
A. 10 mL
B. 20 mL
Correct C. 30 mL
D. 40 mL

Correct Answer: C

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Question 13
A solution contains 0.1 M HCl and 0.2 M NaOH. Determine the pH of the solution.
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 14
A 50 mL sample of 0.5 M HCl is titrated with 1 M NaOH. Calculate the pH of the solution at the equivalence point.
Correct A. 1
B. 2
C. 3
D. 4

Correct Answer: A

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Question 15
A solution contains 0.1 M HCl and 0.1 M NaOH. Determine the pH of the solution.
A. 1
Correct B. 2
C. 3
D. 4

Correct Answer: B

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Question 16
A 25.0 cm$^3$ sample of 0.150 M HCl is titrated with 0.200 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.
A. 12.5 cm$^3$
B. 25.0 cm$^3$
Correct C. 37.5 cm$^3$
D. 50.0 cm$^3$

Correct Answer: C

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Question 17
A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl$_2$ → MCl$_2$. If 2.50 g of M is reacted with 1.00 g of Cl$_2$, what is the limiting reac\tant?
A. M
Correct B. Cl$_2$
C. Neither M nor Cl$_2$ is the limiting reac\tant.
D. Insufficient information to determine the limiting reac\tant.

Correct Answer: B

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Question 18
A 2.00 M solution of H$_2$SO$_4$ is mixed with a 1.00 M solution of NaOH. The reaction is as follows: H$_2$SO$_4$ + 2NaOH → Na$_2$SO$_4$ + 2H$_2$O. What is the pH of the resulting solution?
A. 1.00
Correct B. 2.00
C. 3.00
D. 4.00

Correct Answer: B

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Question 19
A 10.0 g sample of a metal (M) is heated in a crucible until it melts. The resulting liquid is then cooled and solidified. What is the resulting solid?
Correct A. The resulting solid is the same as the original metal.
B. The resulting solid is a different metal.
C. The resulting solid is a compound.
D. The resulting solid is a mixture.

Correct Answer: A

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Question 20
A 5.00 g sample of a metal (M) is reacted with a 10.0 g sample of a non-metal (N) to form a compound. The reaction is as follows: M + N → MN. What is the empirical formula of the resulting compound?
A. M$_2$N
Correct B. MN
C. N$_2$M
D. The empirical formula cannot be determined.

Correct Answer: B

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Question 21
Determine the pH of a 0.1 M solution of HCl, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the concentration of HCl is 0.1 M.
A. 1
B. 2
C. 3
Correct D. 4

Correct Answer: D

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Question 22
A 25 mL sample of 0.5 M NaOH is titrated with 1 M HCl. Calculate the number of moles of HCl required to reach the equivalence point.
A. 0.0125
Correct B. 0.025
C. 0.05
D. 0.1

Correct Answer: B

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Question 23
A polymer has a molecular weight of 50000 g/mol and a degree of polymerization of 100. Calculate the molar mass of the repeating unit.
A. 500
Correct B. 1000
C. 2000
D. 5000

Correct Answer: B

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Question 24
A 2.0 g sample of a hydrocarbon is burned in a bomb calorimeter, relea\sing 4200 J of heat. Calculate the heat of combustion per gram of the hydrocarbon.
A. 2100
Correct B. 4200
C. 6300
D. 8400

Correct Answer: B

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Question 25
A 1.0 M solution of NaOH is titrated with 1.0 M HCl. Calculate the pH of the solution at the equivalence point.
A. 7
Correct B. 8
C. 9
D. 10

Correct Answer: B

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