Practice Post UTME KSU chemistry 2022 Past Questions

Question 1

At 298 K, the s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) if the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol.

Correct A. -110.5 kJ/mol

B. -393.5 kJ/mol

C. 110.5 kJ/mol

D. 393.5 kJ/mol

Correct Answer: A

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Question 2

A 0.500 M solution of NaOH is mixed with a 0.500 M solution of HCl. What is the pH of the resulting solution?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 3

A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?

A. 0.100 M

B. 0.200 M

Correct C. 0.500 M

D. 1.00 M

Correct Answer: C

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Question 4

A 1.00 M solution of H2SO4 is mixed with a 1.00 M solution of NaOH. What is the pH of the resulting solution?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 5

A diagram of a titration setup is shown below. If 35.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?

A. 0.100 M

B. 0.200 M

Correct C. 0.500 M

D. 1.00 M

Correct Answer: C

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Question 6

The reaction of nitrogen dioxide with water is an example of a redox reaction. Write the balanced chemical equation for this reaction.

A. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{H}_2\text{O}

Correct B. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{H}_2\text{O}_2

C. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{H}_2\text{O}_2 + \text{H}_2\text{O}

D. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{H}_2\text{O}_2 + \text{NO}_2

Correct Answer: B

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Question 7

The solubility of a subs\tance is defined as the maximum amount of the subs\tance that can dissolve in a given amount of solvent at a particular temperature. What is the unit of solubility?

A. g/L

Correct B. mol/L

C. g/mol

D. mol/g

Correct Answer: B

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Question 8

The atomic radius of an element is the dis\tance from the nucleus to the outermost electron in a neutral atom. What is the unit of atomic radius?

Correct A. pm

B. nm

C. cm

D. m

Correct Answer: A

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Question 9

The periodic table is arranged in a way that elements with similar properties are placed in the same group. What is the name of the group that contains the noble gases?

A. Group 1

B. Group 2

Correct C. Group 18

D. Group 17

Correct Answer: C

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Question 10

The reaction of hydrogen peroxide with potassium iodide is an example of a redox reaction. Write the balanced chemical equation for this reaction.

Correct A. \text{H}_2\text{O}_2 + 2\text{KI} \rightarrow \text{K}_2\text{O}_2 + 2\text{HI}

B. \text{H}_2\text{O}_2 + 2\text{KI} \rightarrow \text{K}_2\text{O}_2 + \text{H}_2\text{O}

C. \text{H}_2\text{O}_2 + 2\text{KI} \rightarrow \text{K}_2\text{O}_2 + \text{HI}

D. \text{H}_2\text{O}_2 + 2\text{KI} \rightarrow \text{K}_2\text{O}_2 + 2\text{H}_2\text{O}

Correct Answer: A

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Question 11

The rate cons\tant of a first-order reaction is given by the equation \( k = \frac{2.303}{t} \log_{10} left\( \frac{[A]_0}{[A]_t} \right \ \) ). If the initial concentration of the reac\tant is 0.1 M and the concentration at time t is 0.01 M, calculate the rate cons\tant k.

Correct A. 0.01 min^-1

B. 0.1 min^-1

C. 1 min^-1

D. 10 min^-1

Correct Answer: A

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Question 12

A solution contains 0.1 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the concentration of the resulting solution?

A. 0.01 M

Correct B. 0.1 M

C. 1 M

D. 10 M

Correct Answer: B

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Question 13

The s\tandard electrode potential of the Zn^2+/Zn couple is -0.76 V. If the s\tandard electrode potential of the Cu^2+/Cu couple is +0.34 V, what is the s\tandard cell potential of the cell consisting of these two couples?

Correct A. -1.1 V

B. -0.4 V

C. +0.4 V

D. +1.1 V

Correct Answer: A

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Question 14

A diagram of a titration setup is shown below.

A. Titration of HCl with NaOH

Correct B. Titration of NaOH with HCl

C. Titration of H2SO4 with NaOH

D. Titration of NaOH with H2SO4

Correct Answer: B

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Question 15

The half-life of a first-order reaction is 10 minutes. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 20 minutes?

Correct A. 0.01 M

B. 0.05 M

C. 0.1 M

D. 0.5 M

Correct Answer: A

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Question 16

A 2.5 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The temperature of the calorimeter increases by 23.5°C. If the calorimeter cons\tant is 2.5 J/g°C, what is the heat of combustion of the hydrocarbon, assuming it is a pure subs\tance?

A. 100 kJ/mol

B. 200 kJ/mol

Correct C. 300 kJ/mol

D. 400 kJ/mol

Correct Answer: C

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Question 17

A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 1 L of water. What is the concentration of the solution in terms of molality?

Correct A. 0.1 mol/kg

B. 0.2 mol/kg

C. 0.3 mol/kg

D. 0.4 mol/kg

Correct Answer: A

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Question 18

A 2.5 L sample of a gas at 25°C and 1 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 mmHg, what is the partial pressure of the gas?

A. 760 mmHg

Correct B. 736 mmHg

C. 712 mmHg

D. 688 mmHg

Correct Answer: B

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Question 19

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

A. 7.0

Correct B. 7.5

C. 8.0

D. 8.5

Correct Answer: B

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Question 20

A 2.5 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The temperature of the calorimeter increases by 23.5°C. If the calorimeter cons\tant is 2.5 J/g°C, what is the heat of combustion of the hydrocarbon, assuming it is a pure subs\tance?

A. 100 kJ/mol

B. 200 kJ/mol

Correct C. 300 kJ/mol

D. 400 kJ/mol

Correct Answer: C

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Question 21

The reaction of potassium dichromate with sulfuric acid in the presence of iron(II) sulfate is an example of a redox reaction. Write the balanced half-equations for the oxidation and reduction reactions.

A. Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O

Correct B. Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O

C. Fe2+ → Fe3+ + e-

D. Cr3+ + 3e- → Cr

Correct Answer: B

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Question 22

The compound 2,2-dimethylpropane is an example of a branched alkane. Draw the structure of this compound.

A. CH3CH2CH3

B. CH3CH2CH2CH3

Correct C. CH3C(CH3)2CH3

D. CH3CH(CH3)CH3

Correct Answer: C

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Question 23

The reaction of chlorine with sodium hydroxide is an example of a redox reaction. Write the balanced equation for this reaction.

A. 2NaOH + Cl2 → NaCl + NaClO + H2O

Correct B. 2NaOH + Cl2 → NaCl + NaClO + H2O

C. 2NaOH + Cl2 → NaCl + NaClO + H2O

D. 2NaOH + Cl2 → NaCl + NaClO + H2O

Correct Answer: B

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Question 24

The compound 1,2-dimethylcyclohexane is an example of a branched alkane. Draw the structure of this compound.

A. CH3CH2CH2CH3

Correct B. CH3C(CH3)2CH3

C. CH3CH(CH3)CH3

D. CH3CH2CH(CH3)CH3

Correct Answer: B

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Question 25

The reaction of potassium permanganate with sulfuric acid is an example of a redox reaction. Write the balanced half-equations for the oxidation and reduction reactions.

A. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O

Correct B. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O

C. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O

D. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O

Correct Answer: B

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