Practice Post UTME WELLSPRING UNIVERSITY chemistry 2020 Past Questions

Question 1

A sample of gas occupies a volume of 2.5 L at a temperature of 298 K and pressure of 1.2 atm. If the temperature is increased to 323 K while keeping the pressure cons\tant, what is the new volume of the gas?

A. 3.2 L

Correct B. 3.5 L

C. 3.8 L

D. 4.1 L

Correct Answer: B

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Question 2

A solution of HCl is titrated with a solution of NaOH. If 25 mL of 0.1 M HCl is required to neutralize 20 mL of 0.2 M NaOH, what is the concentration of the HCl solution?

Correct A. 0.05 M

B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: A

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Question 3

A diagram of a titration setup is shown below. If the burette contains 0.1 M NaOH and the flask contains 25 mL of 0.2 M HCl, what is the concentration of the NaOH 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 4

A sample of a non-metallic element has a mass of 2.5 g and a volume of 5 mL. If the density of the element is 2.5 g/mL, what is the molar mass of the element?

A. 10 g/mol

Correct B. 20 g/mol

C. 30 g/mol

D. 40 g/mol

Correct Answer: B

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Question 5

A diagram of a periodic table is shown below. Which element has the atomic number 12?

A. Mg

Correct B. Ca

C. K

D. Na

Correct Answer: B

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Question 6

The reaction between sodium hydroxide (NaOH) and acetic acid (CH3COOH) is a classic example of a reaction between a strong base and a weak acid. What is the pH of the resulting solution, given that the initial concentrations of NaOH and CH3COOH are 0.1 M and 0.2 M, respectively?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 7

A 10 mL sample of a solution containing 0.5 M NaCl is added to a 20 mL sample of a solution containing 0.2 M AgNO3. What is the concentration of the resulting solution?

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 8

A polymer is made up of repeating units of the following structure: H2C=CH-COOH. What is the name of this polymer?

Correct A. Polyethylene

B. Polypropylene

C. Polyvinyl chloride

D. Polyacrylonitrile

Correct Answer: A

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Question 9

A solution contains 0.1 M HCl and 0.2 M NaOH. What is the pH of the resulting solution?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 10

A 10 mL sample of a solution containing 0.5 M NaOH is added to a 20 mL sample of a solution containing 0.2 M HCl. What is the concentration of the resulting solution?

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 11

Determine the number of moles of ethene (C2H4) produced when 2.5 g of C2H4 is decomposed at 25°C and 1 atm. The molar mass of C2H4 is 28 g/mol. The decomposition reaction is: C2H4 → C2H2 + H2.

A. 0.089 mol

Correct B. 0.0895 mol

C. 0.090 mol

D. 0.091 mol

Correct Answer: B

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Question 12

A 0.5 L sample of a solution containing 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the pH of the solution after the addition of 20 mL of NaOH.

A. 2.0

B. 2.5

Correct C. 3.0

D. 3.5

Correct Answer: C

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Question 13

A mixture of 2.0 g of NaCl and 1.0 g of KCl is dissolved in 100 mL of water. Calculate the molarity 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 14

A 1.0 L sample of a solution containing 0.1 M H2SO4 is titrated with 0.1 M NaOH. Calculate the number of moles of H2SO4 present in the solution.

A. 0.01 mol

Correct B. 0.02 mol

C. 0.03 mol

D. 0.04 mol

Correct Answer: B

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Question 15

A 2.0 L sample of a solution containing 0.2 M NaOH is titrated with 0.2 M HCl. Calculate the pH of the solution after the addition of 10 mL of HCl.

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 16

The rate cons\tant (k) for a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/\( mol*K \), and the temperature (T) is 300 K, what is the value of the rate cons\tant (k) if the pre-exponential factor (A) is 1.0 x 10^10 s^\( -1 \)?

Correct A. 1.0 x 10^\( -5 \) s^\( -1 \)

B. 1.0 x 10^\( -3 \) s^\( -1 \)

C. 1.0 x 10^\( -2 \) s^\( -1 \)

D. 1.0 x 10^\( -1 \) s^\( -1 \)

Correct Answer: A

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Question 17

A solution contains 0.1 M NH3 and 0.1 M NH4Cl. What is the concentration of OH- ions in the solution?

Correct A. 1.0 x 10^\( -4 \) M

B. 1.0 x 10^\( -3 \) M

C. 1.0 x 10^\( -2 \) M

D. 1.0 x 10^\( -1 \) M

Correct Answer: A

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Question 18

A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer is composed of 80% by weight of a monomer with a molecular weight of 50 g/mol, what is the number-average molecular weight of the polymer?

A. 80,000 g/mol

Correct B. 100,000 g/mol

C. 120,000 g/mol

D. 140,000 g/mol

Correct Answer: B

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Question 19

A solution contains 0.1 M HCl and 0.1 M NaOH. 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 20

A sample of a gas has a volume of 2.0 L at a temperature of 300 K and a pressure of 1.0 atm. What is the volume of the gas at a temperature of 400 K and a pressure of 2.0 atm?

A. 1.0 L

B. 2.0 L

Correct C. 3.0 L

D. 4.0 L

Correct Answer: C

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Question 21

A solution contains 0.1 M H2SO4 and 0.1 M NaOH. What is the concentration of H+ ions in the solution?

Correct A. 1.0 x 10^\( -4 \) M

B. 1.0 x 10^\( -3 \) M

C. 1.0 x 10^\( -2 \) M

D. 1.0 x 10^\( -1 \) M

Correct Answer: A

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Question 22

A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer is composed of 80% by weight of a monomer with a molecular weight of 50 g/mol, what is the number-average molecular weight of the polymer?

A. 80,000 g/mol

Correct B. 100,000 g/mol

C. 120,000 g/mol

D. 140,000 g/mol

Correct Answer: B

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Question 23

A solution contains 0.1 M HCl and 0.1 M NaOH. What is the pH of the solution?

A. 1.0

B. 2.0

C. 3.0

D. 4.0

Correct Answer: VIEW ANSWER

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Question 24

A 2.50 g sample of a metal oxide is heated in a crucible until it decomposes completely. The mass of the metal obtained is 1.25 g. If the metal oxide has a molar mass of 120 g/mol, calculate the percentage yield of the metal.

A. 50%

B. 60%

Correct C. 70%

D. 80%

Correct Answer: C

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Question 25

A solution of 0.100 M HCl is titrated with 0.0500 M NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?

A. 2.00

Correct B. 3.00

C. 4.00

D. 5.00

Correct Answer: B

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