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POST UTME UNILAG 2020 Chemistry | Objective

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Question 1

Determine the pH of a 0.1 M solution of HCl. Assume that the volume of the solution is 1 L.

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 2

A diagram of a titration setup is shown below. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, what is the pH of the resulting solution?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 3

A 1.0 L solution of 0.1 M NaOH is mixed with a 1.0 L solution of 0.1 M HCl. What is the resulting pH?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 4

A diagram of a gas collection apparatus is shown below. If 1.0 L of a gas at 25°C and 1 atm is collected, what is the volume of the gas at 50°C and 2 atm?

Correct A. 2.0 L

B. 3.0 L

C. 4.0 L

D. 5.0 L

Correct Answer: A

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Question 5

A 1.0 L solution of 0.1 M HCl is mixed with a 1.0 L solution of 0.1 M NaOH. What is the resulting pH?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 6

Determine the molar mass of a polymer with the following repeating unit: CH2-CH(CH3)-CH2-CH2-CH2-CH3. Assume that the polymer has a degree of polymerization of 100.

A. 500 g/mol

Correct B. 600 g/mol

C. 700 g/mol

D. 800 g/mol

Correct Answer: B

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Question 7

A 2.5 M solution of NaOH is electrolyzed u\sing a platinum electrode. Calculate the mass of oxygen gas produced at the anode after 2 hours.

A. 0.25 g

Correct B. 0.50 g

C. 0.75 g

D. 1.00 g

Correct Answer: B

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Question 8

The following diagram shows a titration setup. Identify the part labeled A.

Correct A. Burette

B. Beaker

C. Conical flask

D. Pipette

Correct Answer: A

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Question 9

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

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 10

The following diagram shows a periodic table. Identify the element with atomic number 6.

Correct A. Carbon

B. Nitrogen

C. Oxygen

D. Fluorine

Correct Answer: A

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Question 11

Determine the number of moles of oxygen gas (O2) that would be produced at s\tandard temperature and pressure (STP) from the complete combustion of 2.50 g of glu\cose (C6H12O6).

A. 0.125 mol

Correct B. 0.250 mol

C. 0.500 mol

D. 1.00 mol

Correct Answer: B

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Question 12

A 25.0 mL sample of 0.100 M NaOH is mixed with a 25.0 mL sample of 0.100 M HCl. What is the resulting pH of the solution?

A. 7.00

Correct B. 7.25

C. 7.50

D. 8.00

Correct Answer: B

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Question 13

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol?

A. -285.8 kJ/mol

Correct B. -241.8 kJ/mol

C. -393.5 kJ/mol

D. -483.5 kJ/mol

Correct Answer: B

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Question 14

A 1.00 L sample of 0.100 M NaOH is mixed with a 1.00 L sample of 0.100 M HCl. What is the resulting pH of the solution?

A. 7.00

Correct B. 7.25

C. 7.50

D. 8.00

Correct Answer: B

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Question 15

The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. What is the s\tandard enthalpy of formation of N2(g) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?

A. -45.9 kJ/mol

Correct B. -92.0 kJ/mol

C. -135.9 kJ/mol

D. -180.0 kJ/mol

Correct Answer: B

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Question 16

A 0.1 M solution of a weak monoprotic acid HA is titrated with 0.1 M NaOH. If 20 mL of the acid solution is titrated with 15 mL of the base solution, what is the pH of the resulting solution?

A. 3.5

B. 3.8

Correct C. 4.2

D. 4.5

Correct Answer: C

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Question 17

A sample of a polymer has a molecular weight of 100,000 g/mol. If 0.5 g of the polymer is dissolved in 100 mL of a solvent, what is the concentration of the solution in g/L?

A. 0.5 g/L

Correct B. 1.0 g/L

C. 1.5 g/L

D. 2.0 g/L

Correct Answer: B

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Question 18

A metal rod with a length of 2 m and a cross-sectional area of 0.01 m^2 is subjected to a tensile force of 1000 N. What is the stress on the rod?

A. 100 MPa

Correct B. 200 MPa

C. 300 MPa

D. 400 MPa

Correct Answer: B

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Question 19

A 1 M solution of a strong acid HA is titrated with a 1 M solution of a strong base NaOH. If 20 mL of the acid solution is titrated with 15 mL of the base solution, what is the pH of the resulting solution?

A. 7.0

B. 7.5

Correct C. 8.0

D. 8.5

Correct Answer: C

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Question 20

A sample of a metal has a density of 8 g/cm^3. If a 2 g sample of the metal is placed in a 10 mL beaker, what is the volume of the metal in cm^3?

A. 0.25 cm^3

B. 0.5 cm^3

Correct C. 1.0 cm^3

D. 1.5 cm^3

Correct Answer: C

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Question 21

The polymerization of styrene monomers to form polystyrene involves the formation of a new bond between the monomers. Which type of bond is primarily responsible for this polymerization?

Correct A. Covalent bond

B. Ionic bond

C. Hydrogen bond

D. Van der Waals force

Correct Answer: A

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Question 22

A sample of a polymer is analyzed u\sing gel permeation chromatography (GPC). The chromatogram shows a \single peak with a retention time of 10 minutes. What does this indicate about the polymer?

A. The polymer is a homopolymer

B. The polymer is a copolymer

C. The polymer has a high molecular weight

Correct D. The polymer has a low molecular weight

Correct Answer: D

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Question 23

The atomic radius of an atom is defined as the dis\tance from the nucleus to the outermost electron in a neutral atom. Which of the following elements has the largest atomic radius?

A. Hydrogen

B. Helium

C. Lithium

Correct D. Sodium

Correct Answer: D

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Question 24

A redox reaction involves the transfer of electrons from one species to another. Which of the following reactions is an example of a redox reaction?

A. 2H2 + O2 → 2H2O

B. Ca + 2HCl → CaCl2 + H2

Correct C. Fe + CuSO4 → FeSO4 + Cu

D. H2 + Cl2 → 2HCl

Correct Answer: C

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Question 25

A gas is confined to a container with a volume of 2.5 liters. The temperature of the gas is increased from 20°C to 50°C. What is the new volume of the gas?

A. 3.125 liters

Correct B. 4.1667 liters

C. 5 liters

D. 6.25 liters

Correct Answer: B

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