Practice post utme unilorin chemistry 2024 Past Questions

Question 1

A 0.50 M solution of AgNO3 is mixed with a 0.50 M solution of NaCl. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?

A. 0.25 M

B. 0.50 M

Correct C. 1.00 M

D. 1.25 M

Correct Answer: C

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Question 2

A sample of CO2 gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of water vapor is 0.02 atm, what is the mole \fraction of CO2 in the gas mixture?

A. 0.98

B. 0.99

C. 0.995

Correct D. 0.999

Correct Answer: D

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Question 3

A 2.0 L flask contains 1.0 mol of O2 gas at a temperature of 298 K. If the gas is allowed to expand to a volume of 5.0 L, what is the new pressure of the gas?

A. 0.20 atm

Correct B. 0.40 atm

C. 0.60 atm

D. 0.80 atm

Correct Answer: B

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Question 4

A 0.50 M solution of HCl is mixed with a 0.50 M solution of NaOH. If the reaction is allowed to go to completion, what is the pH of the resulting solution?

A. 1.0

B. 2.0

C. 3.0

Correct D. 4.0

Correct Answer: D

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Question 5

A sample of Fe2O3 is heated in a Bunsen burner flame. What is the resulting product?

A. Fe

B. FeO

C. Fe2O3

Correct D. Fe3O4

Correct Answer: D

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Question 6

Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), given that the initial concentrations of NO and O2 are 0.50 M and 0.25 M, respectively, and the rate of reaction is 0.025 M/s after 5 minutes.

A. \( k = 0.005 , \text{M}^{-1} \text{s}^{-1} \)

Correct B. \( k = 0.010 , \text{M}^{-1} \text{s}^{-1} \)

C. \( k = 0.015 , \text{M}^{-1} \text{s}^{-1} \)

D. \( k = 0.020 , \text{M}^{-1} \text{s}^{-1} \)

Correct Answer: B

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Question 7

A 2.50-g sample of an unknown hydrocarbon is burned in a bomb calorimeter, and the heat released is 12.5 kJ. If the combustion equation for the hydrocarbon is CxHy + O2 → CO2 + H2O, and the molar mass of the hydrocarbon is 42.0 g/mol, determine the values of x and y.

Correct A. \( x = 2, , y = 6 \)

B. \( x = 3, , y = 4 \)

C. \( x = 4, , y = 2 \)

D. \( x = 5, , y = 1 \)

Correct Answer: A

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Question 8

A solution containing 0.10 M NH3 and 0.20 M HCl is titrated with 0.10 M NaOH. Determine the pH of the solution after 25.0 mL of NaOH has been added.

A. \( \text{pH} = 9.25 \)

Correct B. \( \text{pH} = 9.50 \)

C. \( \text{pH} = 9.75 \)

D. \( \text{pH} = 10.00 \)

Correct Answer: B

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Question 9

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. Determine the new volume of the gas.

A. \( V = 0.50 , \text{L} \)

B. \( V = 1.00 , \text{L} \)

Correct C. \( V = 1.50 , \text{L} \)

D. \( V = 2.00 , \text{L} \)

Correct Answer: C

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Question 10

A 2.00-g sample of a non-metallic element is heated in a crucible until it sublimes. If the temperature of the crucible is 250°C, and the vapor pressure of the element at this temperature is 1.00 atm, determine the molar mass of the element.

A. \( M = 16.0 , \text{g/mol} \)

Correct B. \( M = 32.0 , \text{g/mol} \)

C. \( M = 48.0 , \text{g/mol} \)

D. \( M = 64.0 , \text{g/mol} \)

Correct Answer: B

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Question 11

The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 25.0 mL of 0.100 M CuSO4(aq) is mixed with 25.0 mL of 0.100 M Zn(NO3)2(aq), what is the limiting reac\tant?

Correct A. Zn(s)

B. CuSO4(aq)

C. Zn(NO3)2(aq)

D. Neither Zn(s) nor CuSO4(aq) is the limiting reac\tant.

Correct Answer: A

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Question 12

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?

Correct A. CH2O

B. C2H4O

C. C3H6O

D. C4H8O

Correct Answer: A

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Question 13

The pH of a 0.100 M solution of a weak acid HA is 4.25. What is the value of Ka for the acid?

Correct A. 1.3 x 10^\( -5 \)

B. 1.3 x 10^\( -4 \)

C. 1.3 x 10^\( -3 \)

D. 1.3 x 10^\( -2 \)

Correct Answer: A

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Question 14

A 25.0 mL sample of a 0.100 M solution of NaOH is titrated with a 0.100 M solution of HCl. What is the pH of the solution after the titration is complete?

Correct A. 7.00

B. 7.25

C. 7.50

D. 7.75

Correct Answer: A

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Question 15

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?

Correct A. CH2O

B. C2H4O

C. C3H6O

D. C4H8O

Correct Answer: A

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Question 16

The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). If 25.0 mL of 0.100 M CuSO4(aq) is mixed with 25.0 mL of 0.100 M Zn(NO3)2(aq), what is the limiting reac\tant?

Correct A. Zn(s)

B. CuSO4(aq)

C. Zn(NO3)2(aq)

D. Neither Zn(s) nor CuSO4(aq) is the limiting reac\tant.

Correct Answer: A

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Question 17

A 2.50 g sample of a compound containing only carbon and hydrogen is analyzed by combustion. The amount of carbon dioxide produced is 1.25 g, and the amount of water produced is 0.750 g. What is the empirical formula of the compound?

Correct A. CH2O

B. C2H4O

C. C3H6O

D. C4H8O

Correct Answer: A

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Question 18

The pH of a 0.100 M solution of a weak acid HA is 4.25. What is the value of Ka for the acid?

Correct A. 1.3 x 10^\( -5 \)

B. 1.3 x 10^\( -4 \)

C. 1.3 x 10^\( -3 \)

D. 1.3 x 10^\( -2 \)

Correct Answer: A

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Question 19

A 25.0 mL sample of a 0.100 M solution of NaOH is titrated with a 0.100 M solution of HCl. What is the pH of the solution after the titration is complete?

A. 7.00

B. 7.25

C. 7.50

D. 7.75

Correct Answer: VIEW ANSWER

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POST UTME UNILORIN 2024 Chemistry | Objective

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