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POST UTME EKSU 2024 Chemistry | Objective

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Question 1

The reaction between methane and chlorine to form chloromethane and hydrogen chloride is an example of a(n)

Correct A. substitution reaction

B. elimination reaction

C. addition reaction

D. condensation reaction

Correct Answer: A

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Question 2

The rate cons\tant (k) of a reaction is related to the activation energy (Ea) by the equation:

Correct A. \ln k = \ln A - \frac{Ea}{RT}

B. \ln k = \ln A + \frac{Ea}{RT}

C. \ln k = \ln A - \frac{RT}{Ea}

D. \ln k = \ln A + \frac{RT}{Ea}

Correct Answer: A

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Question 3

The pH of a solution is 7. If the concentration of hydrogen ions is doubled, the pH will be

A. 6

Correct B. 7

C. 8

D. 9

Correct Answer: B

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Question 4

The balanced equation for the reaction between sodium hydroxide and hydrochloric acid is:

Correct A. 2NaOH + HCl \rightarrow NaCl + H2O

B. 2NaOH + HCl \rightarrow Na2Cl + H2O

C. 2NaOH + HCl \rightarrow NaCl + NaOH

D. 2NaOH + HCl \rightarrow Na2Cl + NaOH

Correct Answer: A

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Question 5

The diagram below shows the titration of a strong acid with a strong base. What is the pH of the solution at the equivalence point?

Correct A. 7

B. 9

C. 10

D. 12

Correct Answer: A

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Question 6

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of C2H6(l) at 298 K.

Correct A. -1570.8 kJ/mol

B. -1470.8 kJ/mol

C. -1370.8 kJ/mol

D. -1670.8 kJ/mol

Correct Answer: A

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Question 7

A solution contains 0.5 M NaCl and 0.2 M CaCl2. Calculate the total concentration of Cl- ions in the solution.

Correct A. 0.7 M

B. 0.6 M

C. 0.5 M

D. 0.4 M

Correct Answer: A

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Question 8

The half-life of a radioactive subs\tance is 5 years. If the initial activity is 1000 Bq, what is the activity after 10 years?

Correct A. 250 Bq

B. 500 Bq

C. 750 Bq

D. 1000 Bq

Correct Answer: A

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Question 9

A 2.0 g sample of a metal is heated in a Bunsen burner flame. The mass of the metal remaining after heating is 1.5 g. What is the percentage increase in mass?

A. 25%

Correct B. 30%

C. 35%

D. 40%

Correct Answer: B

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Question 10

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

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 11

Determine the pH of a 0.1 M solution of HCl at 25°C. The dissociation cons\tant of HCl is 10^\( -7 \).

A. 3

B. 4

C. 5

Correct D. 6

Correct Answer: D

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Question 12

A 2.5 g sample of a polymer is dissolved in 100 mL of a solvent. The osmotic pressure of the solution is 2.5 atm at 25°C. Calculate the molar mass of the polymer.

A. 1000 g/mol

B. 2000 g/mol

Correct C. 3000 g/mol

D. 4000 g/mol

Correct Answer: C

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Question 13

A gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 25°C. Calculate the volume of the gas at a pressure of 3.0 atm and a temperature of 50°C.

A. 1.0 L

Correct B. 1.5 L

C. 2.0 L

D. 2.5 L

Correct Answer: B

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Question 14

A 10 g sample of a subs\tance is burned in a bomb calorimeter. The temperature of the calorimeter increases by 10°C. Calculate the heat of combustion of the subs\tance.

A. -1000 kJ/mol

B. -2000 kJ/mol

Correct C. -3000 kJ/mol

D. -4000 kJ/mol

Correct Answer: C

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Question 15

A 50 mL 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 25 mL of NaOH.

A. 2

B. 3

Correct C. 4

D. 5

Correct Answer: C

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Question 16

The reaction of potassium permanganate with hydrogen peroxide in acidic medium is a classic example of a redox reaction. The reaction is represented by the equation: \( 2KMnO_4 + 3H_2O_2 + H_2SO_4 \rightarrow K_2SO_4 + 2MnSO_4 + 4H_2O + 3O_2 \). What is the oxidation state of manganese in the product MnSO_4?

A. +2

B. +4

Correct C. +6

D. +7

Correct Answer: C

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Question 17

The diagram below represents the structure of a hydrocarbon. What is the name of the hydrocarbon?

A. Cyclohexane

Correct B. Benzene

C. Ethene

D. Propane

Correct Answer: B

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Question 18

The rate cons\tant of a reaction is given by the equation: \( k = Ae^{-E_a/RT} \). What is the unit of the rate cons\tant k?

Correct A. s^-1

B. mol L^-1 s^-1

C. L mol^-1 s^-1

D. mol s^-1

Correct Answer: A

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Question 19

The diagram below represents the energy level diagram of an atom. What is the energy level of the electron in the ground state?

Correct A. n = 1

B. n = 2

C. n = 3

D. n = 4

Correct Answer: A

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Question 20

The reaction of sodium with water is represented by the equation: \( 2Na + 2H_2O \rightarrow 2NaOH + H_2 \). What is the oxidation state of sodium in the product NaOH?

Correct A. +1

B. +2

C. +3

D. +4

Correct Answer: A

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Question 21

Determine the number of moles of nitrogen gas (N2) produced when 2.5 moles of ammonia (NH3) react with an excess of oxygen gas (O2) according to the equation: 4NH3 + 5O2 → 4N2 + 6H2O.

Correct A. 1.25 moles

B. 2.5 moles

C. 5 moles

D. 10 moles

Correct Answer: A

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Question 22

A 2.5 L flask contains 0.5 mol of an ideal gas at 25°C. If the gas is heated to 100°C at cons\tant volume, what is the new pressure?

A. 1.5 atm

B. 2.5 atm

Correct C. 3.5 atm

D. 4.5 atm

Correct Answer: C

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Question 23

A 50 mL sample of a 0.1 M solution of sodium hydroxide (NaOH) is titrated with a 0.1 M solution of hydrochloric acid (HCl). What is the pH of the resulting solution after the reaction is complete?

A. 1

B. 2

Correct C. 7

D. 14

Correct Answer: C

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Question 24

A 2.5 L flask contains 0.5 mol of an ideal gas at 25°C. If the gas is heated to 100°C at cons\tant volume, what is the new pressure?

A. 1.5 atm

B. 2.5 atm

Correct C. 3.5 atm

D. 4.5 atm

Correct Answer: C

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Question 25

A 50 mL sample of a 0.1 M solution of sodium hydroxide (NaOH) is titrated with a 0.1 M solution of hydrochloric acid (HCl). What is the pH of the resulting solution after the reaction is complete?

A. 1

B. 2

Correct C. 7

D. 14

Correct Answer: C

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