POST UTME UNILORIN 2018 Chemistry | Objective

Are you preparing for POST UTME UNILORIN exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2018 Chemistry (Objective) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1
A solution of $NH_4Cl$ in water is prepared by dissolving $10,g$ of $NH_4Cl$ in $100,mL$ of water. Calculate the molar concentration of the solution.
A. 0.1 M
B. 0.2 M
Correct C. 0.5 M
D. 1.0 M

Correct Answer: C

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Question 2
The half-life of a radioactive subs\tance is $10,years$. If the initial amount of the subs\tance is $100,g$, how much of the subs\tance will remain after $20,years$?
A. 20 g
Correct B. 40 g
C. 50 g
D. 60 g

Correct Answer: B

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Question 3
A gas at $27^circ C$ and $1.0,atm$ is compressed to $2.0,atm$. Calculate the final volume of the gas, given that the initial volume is $10,L$.
A. 5.0 L
B. 10 L
Correct C. 20 L
D. 40 L

Correct Answer: C

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Question 4
A solution of $HCl$ in water is prepared by dissolving $20,g$ of $HCl$ in $100,mL$ of water. Calculate the molar concentration of the solution.
A. 0.5 M
Correct B. 1.0 M
C. 2.0 M
D. 5.0 M

Correct Answer: B

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Question 5
A gas at $27^circ C$ and $1.0,atm$ is expanded to $0.5,atm$. Calculate the final volume of the gas, given that the initial volume is $10,L$.
A. 5.0 L
Correct B. 10 L
C. 20 L
D. 40 L

Correct Answer: B

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Question 6
Determine the structure of the compound formed by the reaction between 2-methylpropane and chlorine gas, given that the reaction is carried out in the presence of light.
Correct A. \( CH_3CH_2CH_2CH_2Cl \)
B. \( CH_3CH_2CH_2CH_2CH_2Cl \)
C. \( CH_3CH_2CH_2CH_2CH_2CH_2Cl \)
D. \( CH_3CH_2CH_2CH_2CH_2CH_2CH_2Cl \)

Correct Answer: A

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Question 7
A 0.1 M solution of sodium hydroxide is mixed with a 0.1 M solution of acetic acid. Calculate the pH of the resulting solution.
A. ( 7.0 )
Correct B. ( 7.5 )
C. ( 8.0 )
D. ( 8.5 )

Correct Answer: B

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Question 8
A sample of polystyrene is subjected to a temperature of 100°C for 30 minutes. Calculate the percentage of crystallinity of the sample.
A. ( 20% )
B. ( 30% )
Correct C. ( 40% )
D. ( 50% )

Correct Answer: C

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Question 9
A 1.0 M solution of potassium permanganate is titrated with a 1.0 M solution of oxalic acid. Calculate the number of moles of oxalic acid required to react with 50 mL of the potassium permanganate solution.
A. ( 0.05 ) mol
Correct B. ( 0.10 ) mol
C. ( 0.15 ) mol
D. ( 0.20 ) mol

Correct Answer: B

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Question 10
A 0.1 M solution of sodium hydroxide is mixed with a 0.1 M solution of hydrochloric acid. Calculate the concentration of the resulting 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 11
Determine the molar solubility of AgCl in a 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) for AgCl is 1.8 x 10^-10.
A. 1.0 x 10^-5 M
Correct B. 1.5 x 10^-5 M
C. 2.0 x 10^-5 M
D. 3.0 x 10^-5 M

Correct Answer: B

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Question 12
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. 2.50
Correct C. 3.00
D. 3.50

Correct Answer: C

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Question 13
A 50.0 g sample of a metal oxide is heated in a crucible until it is completely reduced to the metal. If the mass of the metal produced is 35.0 g, calculate the percentage yield of the reaction.
A. 70%
B. 75%
Correct C. 80%
D. 85%

Correct Answer: C

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Question 14
A 100.0 mL sample of a solution containing 0.100 M Cu2+ ions is titrated with 0.100 M Na2S. Calculate the number of moles of Cu2+ ions present in the original solution.
A. 0.0100 mol
Correct B. 0.0150 mol
C. 0.0200 mol
D. 0.0250 mol

Correct Answer: B

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Question 15
A 50.0 g sample of a metal hydroxide is dissolved in water to form a solution containing 0.100 M OH- ions. Calculate the concentration of the metal ions in the solution.
A. 0.0500 M
B. 0.0750 M
Correct C. 0.100 M
D. 0.125 M

Correct Answer: C

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Question 16
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 equation: 2H2 + O2 → 2H2O.
Correct A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 10 moles

Correct Answer: A

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Question 17
A 10.0 mL sample of a solution containing 0.1 M NaCl is titrated with 0.1 M AgNO3. Calculate the number of moles of NaCl present in the sample.
A. 0.001 moles
B. 0.01 moles
Correct C. 0.1 moles
D. 1 mole

Correct Answer: C

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Question 18
A solution containing 0.5 M H2SO4 is mixed with a solution containing 0.5 M NaOH. Calculate the pH of the resulting solution.
A. 1
Correct B. 2
C. 7
D. 14

Correct Answer: B

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Question 19
A 2.0 L sample of a gas at 25°C and 1 atm is collected over water. Calculate the partial pressure of the gas.
Correct A. 0.5 atm
B. 1 atm
C. 1.5 atm
D. 2 atm

Correct Answer: A

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Question 20
A 5.0 g sample of a subs\tance is found to have a mass of 2.5 g when dried. Calculate the percentage of water in the subs\tance.
A. 20%
Correct B. 30%
C. 40%
D. 50%

Correct Answer: B

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