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POST UTME UI 2020 Chemistry | Objective

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Question 1

The reaction of zinc metal with copper(II) sulfate solution is a classic example of a redox reaction. Write the balanced equation for this reaction, including the state of each subs\tance.

Correct A. Zn + CuSO4 → ZnSO4 + Cu

B. Zn + CuSO4 → ZnSO4 + Cu2O

C. Zn + CuSO4 → ZnSO4 + CuSO3

D. Zn + CuSO4 → ZnSO4 + Cu(OH)2

Correct Answer: A

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Question 2

A metal M reacts with chlorine gas to form a white solid MX. The molar mass of M is 55.85 g/mol, and the molar mass of Cl2 is 70.90 g/mol. What is the molar mass of MX?

A. 125.75 g/mol

Correct B. 126.75 g/mol

C. 127.75 g/mol

D. 128.75 g/mol

Correct Answer: B

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Question 3

The following diagram shows a setup for the electrolysis of a solution of sodium chloride. What is the product at the cathode?

Correct A. Na

B. Cl2

C. H2

D. NaCl

Correct Answer: A

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Question 4

The following diagram shows a setup for the extraction of a metal from its ore. What is the purpose of the electrolyte in the cell?

Correct A. To conduct electricity

B. To purify the metal

C. To increase the temperature

D. To decrease the pressure

Correct Answer: A

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Question 5

The following diagram shows a setup for the distillation of a mixture of two liquids. What is the purpose of the condenser?

A. To increase the temperature

B. To decrease the pressure

C. To purify the mixture

Correct D. To separate the liquids

Correct Answer: D

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Question 6

Determine the pH of a 0.1 M solution of HCl. The dissociation cons\tant of HCl is 10^-7.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 7

Calculate the number of moles of NaOH required to react with 250 mL of 0.5 M HCl.

Correct A. 0.125

B. 0.25

C. 0.5

D. 1

Correct Answer: A

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Question 8

Identify the type of reaction that occurs when ethanol (C2H5OH) reacts with HCl.

A. Synthesis

B. Decomposition

Correct C. Substitution

D. Elimination

Correct Answer: C

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Question 9

A 2.5 g sample of a non-metallic oxide is heated in a stream of CO2 gas. The mass of the oxide decreases by 1.5 g. What is the empirical formula of the oxide?

A. CO

Correct B. CO2

C. C2O

D. C3O2

Correct Answer: B

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Question 10

A metal (M) reacts with HCl to produce a salt and hydrogen gas. The reaction is as follows: M + 2HCl -> MHCl2 + H2. If 2.5 g of M reacts with 10 mL of 1 M HCl, what is the molar mass of M?

A. 50

B. 75

Correct C. 100

D. 125

Correct Answer: C

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Question 11

The s\tandard electrode potential of the couple Mn2+/Mn is -1.18 V. Calculate the s\tandard electrode potential of the couple MnO4-/Mn2+.

Correct A. -0.90 V

B. -1.18 V

C. 0.90 V

D. 1.18 V

Correct Answer: A

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Question 12

A solution containing 0.1 M NaCl is electrolyzed u\sing a platinum electrode. Calculate the mass of chlorine gas liberated at the anode after 2 hours.

A. 0.12 g

Correct B. 0.24 g

C. 0.36 g

D. 0.48 g

Correct Answer: B

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Question 13

The solubility product cons\tant (Ksp) of AgCl is 1.8 x 10^-10. Calculate the molar solubility of AgCl.

A. 1.0 x 10^-5 M

Correct B. 1.0 x 10^-6 M

C. 1.0 x 10^-7 M

D. 1.0 x 10^-8 M

Correct Answer: B

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Question 14

A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. Calculate the molar mass of the repeating unit.

A. 200 g/mol

Correct B. 400 g/mol

C. 600 g/mol

D. 800 g/mol

Correct Answer: B

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Question 15

A solution containing 0.1 M glu\cose is electrolyzed u\sing a platinum electrode. Calculate the mass of oxygen gas liberated at the anode after 2 hours.

A. 0.12 g

Correct B. 0.24 g

C. 0.36 g

D. 0.48 g

Correct Answer: B

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Question 16

The rate cons\tant of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?

Correct A. 0.01 M

B. 0.05 M

C. 0.1 M

D. 0.2 M

Correct Answer: A

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Question 17

The reaction 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant of 0.02 L mol^-1 s^-1. If the initial concentrations of NO and O2 are 0.1 M and 0.05 M, respectively, what is the rate of reaction after 10 seconds?

A. 0.001 M s^-1

B. 0.01 M s^-1

Correct C. 0.02 M s^-1

D. 0.1 M s^-1

Correct Answer: C

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Question 18

The reaction 2NH3(g) + 3O2(g) → 2NO(g) + 3H2O(g) has a rate cons\tant of 0.01 L mol^-1 s^-1. If the initial concentrations of NH3 and O2 are 0.05 M and 0.1 M, respectively, what is the rate of reaction after 20 seconds?

A. 0.0001 M s^-1

B. 0.001 M s^-1

Correct C. 0.01 M s^-1

D. 0.1 M s^-1

Correct Answer: C

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Question 19

The reaction 2H2(g) + O2(g) → 2H2O(g) has a rate cons\tant of 0.02 L mol^-1 s^-1. If the initial concentrations of H2 and O2 are 0.1 M and 0.05 M, respectively, what is the rate of reaction after 15 seconds?

A. 0.0005 M s^-1

B. 0.005 M s^-1

Correct C. 0.01 M s^-1

D. 0.05 M s^-1

Correct Answer: C

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Question 20

The reaction 2CH4(g) + 3O2(g) → 2CO2(g) + 4H2O(g) has a rate cons\tant of 0.01 L mol^-1 s^-1. If the initial concentrations of CH4 and O2 are 0.05 M and 0.1 M, respectively, what is the rate of reaction after 25 seconds?

A. 0.0002 M s^-1

B. 0.002 M s^-1

Correct C. 0.01 M s^-1

D. 0.1 M s^-1

Correct Answer: C

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Question 21

The entropy change for the reaction 2NO(g) → N2(g) + O2(g) is 180 J/K. If the reaction occurs at 298 K, what is the s\tandard enthalpy change (ΔH°) for the reaction?

Correct A. -180 kJ/mol

B. -90 kJ/mol

C. -45 kJ/mol

D. -22.5 kJ/mol

Correct Answer: A

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Question 22

A 0.5 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 1 L of water. What is the concentration of Cl- ions in the solution?

A. 0.5 M

Correct B. 0.25 M

C. 0.1 M

D. 0.05 M

Correct Answer: B

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Question 23

A polymer has a molecular weight of 100,000 g/mol. If 1 g of the polymer is dissolved in 100 mL of water, what is the concentration of the polymer in the solution?

A. 1 g/L

Correct B. 10 g/L

C. 100 g/L

D. 1000 g/L

Correct Answer: B

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Question 24

A 2 M solution of HCl is prepared by dissolving 40 g of HCl in 1 L of water. What is the concentration of H+ ions in the solution?

Correct A. 2 M

B. 1 M

C. 0.5 M

D. 0.25 M

Correct Answer: A

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Question 25

A 1 M solution of NaOH is prepared by dissolving 40 g of NaOH in 1 L of water. What is the concentration of OH- ions in the solution?

Correct A. 1 M

B. 0.5 M

C. 0.25 M

D. 0.1 M

Correct Answer: A

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