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POST UTME BELLS UNIVERSITY 2018 Chemistry | Objective

Are you preparing for POST UTME BELLS UNIVERSITY 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

The element with atomic number 12 is classified as a metal in the periodic table. What is the name of this element?

Correct A. Magnesium

B. Silicon

C. Manganese

D. Copper

Correct Answer: A

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Question 2

A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of Na+ ions in the solution?

Correct A. 0.01 M

B. 0.1 M

C. 0.5 M

D. 1.0 M

Correct Answer: A

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Question 3

A sample of a polymer is analyzed and found to have a molecular weight of 50,000 g/mol. What is the degree of polymerization of the polymer?

A. 10

Correct B. 50

C. 100

D. 500

Correct Answer: B

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Question 4

A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of Cl- ions in the solution?

A. 0.01 M

Correct B. 0.1 M

C. 0.5 M

D. 1.0 M

Correct Answer: B

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Question 5

A sample of a gas is analyzed and found to have a volume of 2.5 L at a pressure of 1.0 atm and a temperature of 298 K. What is the number of moles of gas present?

A. 0.01 mol

B. 0.1 mol

Correct C. 1.0 mol

D. 10 mol

Correct Answer: C

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Question 6

The solubility of a subs\tance is defined as the maximum amount of the subs\tance that can dissolve in a given amount of solvent at a particular temperature. What is the term for the minimum amount of solvent required to dissolve a given amount of solute?

A. Critical Micelle Concentration

B. Solubility Limit

Correct C. Minimum Dissolving Solvent

D. Saturated Solution

Correct Answer: C

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Question 7

A hydrocarbon has the molecular formula C6H14. What is the name of the compound?

Correct A. Hexane

B. Hep\tane

C. Oc\tane

D. Nonane

Correct Answer: A

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Question 8

A solution contains 2.5 g of NaCl in 100 mL of water. What is the molarity of the solution?

A. 0.25 M

Correct B. 0.5 M

C. 1.0 M

D. 2.0 M

Correct Answer: B

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Question 9

A sample of air contains 20% oxygen, 70% nitrogen, and 10% carbon dioxide by volume. What is the partial pressure of oxygen in the air at 1 atm total pressure?

Correct A. 0.2 atm

B. 0.4 atm

C. 0.6 atm

D. 0.8 atm

Correct Answer: A

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Question 10

A 2.0 M solution of HCl is mixed with a 2.0 M solution of NaOH. What is the pH of the resulting solution?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

Determine the rate cons\tant (k) for the first-order reaction: ln\( [A]t/[A]0 \) = -kt, given that the initial concentration of A is 0.1 M and the concentration at time t is 0.01 M.

Correct A. \( k = \frac{1}{t} lnleft\( \frac{[A]_0}{[A]_t}\right \ \) )

B. \( k = \frac{1}{[A]_0} lnleft\( \frac{[A]_t}{[A]_0}\right \ \) )

C. \( k = \frac{1}{t} lnleft\( \frac{[A]_t}{[A]_0}\right \ \) )

D. \( k = \frac{1}{[A]_t} lnleft\( \frac{[A]_0}{[A]_t}\right \ \) )

Correct Answer: A

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Question 12

A polymer has a molecular weight of 50000 g/mol and a degree of polymerization of 200. What is the molar mass of the monomer?

Correct A. \( 250 , \text{g/mol} \)

B. \( 500 , \text{g/mol} \)

C. \( 1000 , \text{g/mol} \)

D. \( 2000 , \text{g/mol} \)

Correct Answer: A

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Question 13

A solution contains 0.1 M NaCl. What is the concentration of Cl^- ions in the solution?

Correct A. \( 0.05 , \text{M} \)

B. \( 0.1 , \text{M} \)

C. \( 0.2 , \text{M} \)

D. \( 0.5 , \text{M} \)

Correct Answer: A

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Question 14

A buffer solution contains 0.1 M NH4Cl and 0.1 M NH3. What is the pH of the solution?

A. ( 9 )

Correct B. ( 10 )

C. ( 11 )

D. ( 12 )

Correct Answer: B

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Question 15

A 2.5 L solution contains 0.2 M NaOH. What is the number of moles of NaOH in the solution?

A. \( 0.05 , \text{mol} \)

Correct B. \( 0.1 , \text{mol} \)

C. \( 0.15 , \text{mol} \)

D. \( 0.2 , \text{mol} \)

Correct Answer: B

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Question 16

The reaction between potassium dichromate and sulfuric acid is a redox reaction. Write the balanced half-equations for the oxidation and reduction reactions.

A. Cr2O72- + 14H+ → 2Cr3+ + 7H2O

B. Cr2O72- + 6H+ → 2Cr3+ + 3H2O

Correct C. Cr2O72- + 8H+ → 2Cr3+ + 4H2O

D. Cr2O72- + 10H+ → 2Cr3+ + 5H2O

Correct Answer: C

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Question 17

A solution of 0.1 M NaCl is mixed with a solution of 0.1 M AgNO3. What is the concentration of the chloride ion in the resulting solution?

A. 0.05 M

Correct B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: B

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Question 18

A sample of 2.5 g of a subs\tance is dissolved in 50 mL of water. What is the concentration of the solution in g/L?

A. 0.05 g/L

B. 0.1 g/L

Correct C. 0.5 g/L

D. 1 g/L

Correct Answer: C

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Question 19

A solution of 0.1 M HCl is mixed with a solution of 0.1 M NaOH. What is the pH of the resulting solution?

A. 1

Correct B. 7

C. 10

D. 14

Correct Answer: B

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Question 20

A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?

A. To measure the volume of the solution

B. To mix the solutions

Correct C. To add the titrant

D. To measure the pH of the solution

Correct Answer: C

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Question 21

A diagram of a chromatography setup is shown below. What is the purpose of the stationary phase in this setup?

Correct A. To separate the components of the mixture

B. To identify the components of the mixture

C. To measure the concentration of the components

D. To determine the pH of the mixture

Correct Answer: A

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Question 22

A diagram of a spectrophotometer setup is shown below. What is the purpose of the detector in this setup?

Correct A. To measure the absorbance of the solution

B. To measure the transmit\tance of the solution

C. To measure the concentration of the solution

D. To determine the pH of the solution

Correct Answer: A

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Question 23

A diagram of a distillation setup is shown below. What is the purpose of the condenser in this setup?

A. To separate the components of the mixture

B. To identify the components of the mixture

C. To measure the concentration of the components

D. To determine the pH of the mixture

Correct Answer: VIEW ANSWER

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Question 24

A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.1 g, calculate the percentage yield of the metal oxide.

A. 85%

B. 90%

Correct C. 92%

D. 95%

Correct Answer: C

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Question 25

The reaction between sodium hydroxide and hydrochloric acid is represented by the equation: NaOH + HCl → NaCl + H2O. If 25 cm3 of 0.1 M NaOH is added to 25 cm3 of 0.1 M HCl, calculate the number of moles of NaCl produced.

A. 0.005 mol

Correct B. 0.01 mol

C. 0.015 mol

D. 0.02 mol

Correct Answer: B

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