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POST UTME OSUSTECH 2024 Chemistry | Objective

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Question 1

Determine the number of moles of $\text{CO}_2$ produced when 2.50 g of $\text{CaCO}_3$ is completely decomposed at 1000 K and 1 atm.

Correct A. 0.0250 mol

B. 0.0500 mol

C. 0.100 mol

D. 0.200 mol

Correct Answer: A

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Question 2

The s\tandard enthalpy of formation of $\text{CaCO}_3(s)$ is $-1204.3 \text{ kJ/mol}$. Calculate the s\tandard enthalpy of formation of $\text{CaO}(s)$.

A. -1204.3 kJ/mol

B. -1204.3 + 178.2 kJ/mol

Correct C. -1204.3 - 178.2 kJ/mol

D. -1204.3 + 178.2 + 393.5 kJ/mol

Correct Answer: C

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Question 3

A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M $\text{NaOH}$ is required to neutralize 20.0 mL of a weak acid, what is the concentration of the acid?

A. 0.0500 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 4

The entropy change for the vaporization of water at 373 K is $\Delta S = 109 \text{ J/mol} \cdot \text{K}$. Calculate the s\tandard enthalpy of vaporization of water at 373 K.

Correct A. 44.1 kJ/mol

B. 44.1 + 109 J/mol

C. 44.1 - 109 J/mol

D. 44.1 + 109 kJ/mol

Correct Answer: A

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Question 5

A diagram of a polymer chain is shown below. If the polymer has a molecular weight of 100,000 g/mol, what is the degree of polymerization?

A. 500

B. 1000

C. 5000

Correct D. 10,000

Correct Answer: D

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Question 6

Determine the type of reaction that occurs when 1-bromopropane reacts with sodium hydroxide in ethanol.

Correct A. Substitution reaction

B. Elimination reaction

C. Addition reaction

D. Condensation reaction

Correct Answer: A

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Question 7

Calculate the molar mass of a compound with the empirical formula C3H6O.

A. 60 g/mol

B. 90 g/mol

Correct C. 120 g/mol

D. 180 g/mol

Correct Answer: C

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Question 8

A 2.0 M solution of HCl is mixed with a 1.0 M solution of NaOH. What is the pH of the resulting solution?

A. 1.0

Correct B. 2.0

C. 3.0

D. 4.0

Correct Answer: B

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Question 9

A sample of CO2 gas occupies a volume of 2.5 L at a pressure of 1.5 atm. What is the volume of the gas at a pressure of 3.0 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 10

A 10.0 g sample of a compound is dissolved in 100.0 mL of water. What is the molarity of the solution?

A. 0.1 M

B. 0.5 M

Correct C. 1.0 M

D. 5.0 M

Correct Answer: C

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Question 11

Determine the s\tandard enthalpy of formation of CO2(g) from the following data: ΔHf(CO2(g)) = -393.5 kJ/mol, ΔHf(C) = 0 kJ/mol, ΔHf(O2(g)) = 0 kJ/mol.

Correct A. -393.5 kJ/mol

B. -393.5 kJ/mol + 0 kJ/mol

C. -393.5 kJ/mol + 0 kJ/mol + 0 kJ/mol

D. -393.5 kJ/mol + 0 kJ/mol + 0 kJ/mol + 0 kJ/mol

Correct Answer: A

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Question 12

A 0.500 M solution of NaCl is electrolyzed u\sing a platinum electrode. If the cell potential is 2.71 V, what is the mass of Cl2(g) produced at the anode in 2.00 hours?

Correct A. 0.250 g

B. 0.500 g

C. 1.00 g

D. 2.00 g

Correct Answer: A

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Question 13

The following reaction occurs at 298 K: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l). If ΔH = -890 kJ/mol, what is the s\tandard enthalpy of formation of CH4(g)?

Correct A. -74.8 kJ/mol

B. -74.8 kJ/mol + 393.5 kJ/mol

C. -74.8 kJ/mol + 393.5 kJ/mol + 2$ 0 kJ/mol $

D. -74.8 kJ/mol + 393.5 kJ/mol + 2$ 0 kJ/mol $ + 2$ 0 kJ/mol $

Correct Answer: A

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Question 14

A 1.00 M solution of HCl is electrolyzed u\sing a platinum electrode. If the cell potential is 2.00 V, what is the mass of H2(g) produced at the cathode in 2.00 hours?

Correct A. 0.500 g

B. 1.00 g

C. 2.00 g

D. 4.00 g

Correct Answer: A

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Question 15

The following reaction occurs at 298 K: 2CH4(g) + 3O2(g) → 2CO2(g) + 4H2O(l). If ΔH = -2210 kJ/mol, what is the s\tandard enthalpy of formation of O2(g)?

Correct A. 0 kJ/mol

B. 0 kJ/mol + 393.5 kJ/mol

C. 0 kJ/mol + 393.5 kJ/mol + 2$ 0 kJ/mol $

D. 0 kJ/mol + 393.5 kJ/mol + 2$ 0 kJ/mol $ + 2$ 0 kJ/mol $

Correct Answer: A

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Question 16

A 2.5 M solution of HCl is prepared by dissolving 25 g of HCl in 1000 mL of water. Calculate the number of moles of HCl dissolved.

Correct A. 0.0025 mol

B. 0.025 mol

C. 0.25 mol

D. 2.5 mol

Correct Answer: A

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Question 17

A 0.1 M solution of NaOH is prepared by dissolving 0.1 mol of NaOH in 1 L of water. Calculate the concentration of the solution in g/L.

A. 2 g/L

Correct B. 4 g/L

C. 6 g/L

D. 8 g/L

Correct Answer: B

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Question 18

A 2 M solution of H2SO4 is prepared by dissolving 2 mol of H2SO4 in 1 L of water. Calculate the concentration of the solution in g/L.

A. 100 g/L

B. 150 g/L

Correct C. 200 g/L

D. 250 g/L

Correct Answer: C

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Question 19

A 0.1 M solution of NaOH is prepared by dissolving 0.1 mol of NaOH in 1 L of water. Calculate the concentration of the solution in g/L.

A. 2 g/L

Correct B. 4 g/L

C. 6 g/L

D. 8 g/L

Correct Answer: B

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Question 20

A 2.5 M solution of HCl is prepared by dissolving 25 g of HCl in 1000 mL of water. Calculate the number of moles of HCl dissolved.

Correct A. 0.0025 mol

B. 0.025 mol

C. 0.25 mol

D. 2.5 mol

Correct Answer: A

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Question 21

A 0.1 M solution of NaOH is prepared by dissolving 0.1 mol of NaOH in 1 L of water. Calculate the concentration of the solution in g/L.

A. 2 g/L

Correct B. 4 g/L

C. 6 g/L

D. 8 g/L

Correct Answer: B

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Question 22

A 2 M solution of H2SO4 is prepared by dissolving 2 mol of H2SO4 in 1 L of water. Calculate the concentration of the solution in g/L.

A. 100 g/L

B. 150 g/L

Correct C. 200 g/L

D. 250 g/L

Correct Answer: C

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Question 23

A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. If the initial pH of the acid solution is 3.5, what is the pH of the solution after the addition of 20 mL of 0.1 M NaOH?

A. 4.5

Correct B. 5.5

C. 6.5

D. 7.5

Correct Answer: B

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Question 24

A polymer has a molecular weight of 50000 g/mol and a degree of polymerization of 100. What is the molar mass of the repeating unit of the polymer?

Correct A. 500 g/mol

B. 5000 g/mol

C. 50000 g/mol

D. 500000 g/mol

Correct Answer: A

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Question 25

A catalyst is added to a reaction mixture containing 2.0 g of reac\tant A and 1.0 g of reac\tant B. If the reaction is 50% complete after 10 minutes, what is the amount of product formed?

A. 0.5 g

Correct B. 1.0 g

C. 1.5 g

D. 2.0 g

Correct Answer: B

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