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POST UTME ESUT 2020 Chemistry | Objective

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Question 1

Determine the pH of a 0.1 M solution of HCl.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 2

A diagram of a titration setup is shown below. What is the purpose of the burette?

A. To measure the volume of the acid

Correct B. To measure the volume of the base

C. To mix the acid and base

D. To measure the pH of the solution

Correct Answer: B

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Question 3

The atomic radius of an element increases down a group in the periodic table. Explain this tr\end.

A. Due to the increase in atomic number

B. Due to the increase in atomic mass

Correct C. Due to the increase in the number of energy levels

D. Due to the increase in the number of electrons

Correct Answer: C

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Question 4

A diagram of a gas molecule is shown below. What is the shape of the molecule?

A. Linear

B. Trigonal planar

C. Tetrahedral

Correct D. Bent

Correct Answer: D

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Question 5

The pH of a solution is 7. What is the concentration of the hydrogen ions?

Correct A. 1 x 10^\( -7 \) M

B. 1 x 10^\( -6 \) M

C. 1 x 10^\( -5 \) M

D. 1 x 10^\( -4 \) M

Correct Answer: A

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Question 6

A 2.50 g sample of an unknown hydrocarbon is burned in a bomb calorimeter. The temperature of the calorimeter increases by 2.35°C. If the heat capacity of the calorimeter is 1.50 kJ/°C, what is the average bond energy of the hydrocarbon?

A. 400 kJ/mol

B. 450 kJ/mol

Correct C. 500 kJ/mol

D. 550 kJ/mol

Correct Answer: C

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Question 7

A solution of 0.250 M NaCl is prepared by dissolving 10.0 g of NaCl in 1.00 L of water. What is the concentration of Cl- ions in the solution?

A. 0.125 M

Correct B. 0.250 M

C. 0.500 M

D. 1.00 M

Correct Answer: B

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Question 8

A 1.00 L sample of a gas at 25°C and 1.00 atm is compressed to 2.00 atm at cons\tant temperature. What is the new volume of the gas?

A. 0.500 L

Correct B. 0.750 L

C. 1.00 L

D. 1.25 L

Correct Answer: B

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Question 9

A mixture of 25.0 g of ethanol (C2H5OH) and 15.0 g of water (H2O) is heated to produce a vapor mixture. What is the mole \fraction of ethanol in the vapor phase?

A. 0.625

B. 0.750

Correct C. 0.875

D. 1.00

Correct Answer: C

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Question 10

A 1.00 M solution of NaOH is prepared by dissolving 40.0 g of NaOH in 1.00 L of water. What is the pH of the solution?

A. 13.0

B. 13.5

Correct C. 14.0

D. 14.5

Correct Answer: C

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Question 11

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the volume of HCl in liters?

A. 0.25 L

Correct B. 0.5 L

C. 0.75 L

D. 1 L

Correct Answer: B

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Question 12

A gas at 300 K has a volume of 2.5 L. If the temperature is increased to 400 K, what is the new volume of the gas?

A. 3.125 L

B. 3.5 L

Correct C. 4 L

D. 4.5 L

Correct Answer: C

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Question 13

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the number of moles of HCl?

A. 0.0025 mol

Correct B. 0.005 mol

C. 0.0075 mol

D. 0.01 mol

Correct Answer: B

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Question 14

A gas at 300 K has a volume of 2.5 L. If the temperature is increased to 400 K, what is the new volume of the gas?

A. 3.125 L

B. 3.5 L

Correct C. 4 L

D. 4.5 L

Correct Answer: C

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Question 15

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the number of moles of NaOH?

A. 0.0025 mol

Correct B. 0.005 mol

C. 0.0075 mol

D. 0.01 mol

Correct Answer: B

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Question 16

Determine the number of moles of electrons transferred during the electrolysis of a solution of copper(II) sulfate u\sing a current of 2.5 A for 2.0 hours. The s\tandard reduction potential of copper(II) ion is -0.34 V.

A. 0.5 mol

Correct B. 1.0 mol

C. 1.5 mol

D. 2.0 mol

Correct Answer: B

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Question 17

A sample of nitrogen gas occupies a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 298 K. Calculate the number of moles of nitrogen gas present in the sample.

A. 0.1 mol

Correct B. 0.2 mol

C. 0.3 mol

D. 0.4 mol

Correct Answer: B

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Question 18

The s\tandard enthalpy of formation of carbon dioxide is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of methane (CH4) if the s\tandard enthalpy of formation of carbon is -74.8 kJ/mol and the s\tandard enthalpy of formation of hydrogen gas is 0 kJ/mol.

A. -74.8 kJ/mol

B. -50.5 kJ/mol

C. -74.8 kJ/mol

Correct D. -50.5 kJ/mol

Correct Answer: D

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Question 19

A 0.50 M solution of sodium hydroxide (NaOH) is mixed with a 0.50 M solution of hydrochloric acid (HCl). Calculate the pH of the resulting solution.

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 20

A sample of sulfur dioxide gas occupies a volume of 3.0 L at a pressure of 2.0 atm and a temperature of 300 K. Calculate the number of moles of sulfur dioxide gas present in the sample.

A. 0.2 mol

Correct B. 0.3 mol

C. 0.4 mol

D. 0.5 mol

Correct Answer: B

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Question 21

Calculate the s\tandard enthalpy change for the reaction: 2Ag+(aq) + Cr2O72-(aq) → 2Ag(s) + 2Cr3+(aq) + 7H2O(l). Given that ΔH°\( Ag+\( aq \ \) → Ag(s)) = 105.9 kJ/mol and ΔH°\( Cr2O72-\( aq \ \) → Cr3+(aq)) = -1364.4 kJ/mol.

Correct A. -1200 kJ/mol

B. -1500 kJ/mol

C. -1800 kJ/mol

D. -2000 kJ/mol

Correct Answer: A

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Question 22

A metal M has an atomic radius of 135 pm. If the first ionization energy of M is 520 kJ/mol, what is the electron affinity of M?

A. -100 kJ/mol

Correct B. -150 kJ/mol

C. -200 kJ/mol

D. -250 kJ/mol

Correct Answer: B

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Question 23

The s\tandard Gibbs free energy change for the reaction: 2H2(g) + O2(g) → 2H2O(l) is -237 kJ/mol. What is the equilibrium cons\tant (K) for this reaction?

A. 10^\( -10 \)

B. 10^\( -5 \)

C. 10^\( -1 \)

Correct D. 10^5

Correct Answer: D

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Question 24

A solution contains 0.1 M AgNO3 and 0.1 M NaCl. What is the concentration of Ag+ ions in the 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 25

A 2.5 L flask contains 0.5 M H2(g). What is the partial pressure of H2(g) in the flask?

A. 0.1 atm

Correct B. 0.2 atm

C. 0.3 atm

D. 0.4 atm

Correct Answer: B

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