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POST UTME MADONNA UNIVERSITY 2024 Chemistry | Objective

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Question 1

A 0.5 M solution of AgNO3 is prepared by dissolving 25.0 g of AgNO3 in 1.0 L of water. What is the molarity of the solution if 25.0 g of AgNO3 is used to prepare 2.0 L of solution?

A. 0.5 M

B. 1.0 M

C. 2.0 M

Correct D. 0.25 M

Correct Answer: D

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Question 2

A sample of a gas occupies 2.5 L at 25°C and 1.0 atm. What is the volume of the gas at 50°C and 2.0 atm?

Correct A. 1.25 L

B. 2.5 L

C. 5.0 L

D. 10.0 L

Correct Answer: A

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Question 3

A 2.0 M solution of HCl is prepared by dissolving 40.0 g of HCl in 1.0 L of water. What is the mass of HCl required to prepare 1.0 L of 1.0 M solution?

Correct A. 20.0 g

B. 40.0 g

C. 60.0 g

D. 80.0 g

Correct Answer: A

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Question 4

A 1.0 M solution of NaOH is prepared by dissolving 40.0 g of NaOH in 1.0 L of water. What is the molarity of the solution if 40.0 g of NaOH is used to prepare 2.0 L of solution?

A. 0.5 M

Correct B. 1.0 M

C. 2.0 M

D. 4.0 M

Correct Answer: B

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Question 5

A sample of a gas occupies 1.5 L at 20°C and 1.5 atm. What is the pressure of the gas at 30°C and 2.0 atm?

A. 1.0 atm

B. 1.5 atm

Correct C. 2.0 atm

D. 3.0 atm

Correct Answer: C

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Question 6

A 0.500 M solution of AgNO3 is mixed with a 0.500 M solution of NaCl. What is the concentration of AgCl that precipitates out of the solution?

A. 0.250 M

Correct B. 0.333 M

C. 0.500 M

D. 0.667 M

Correct Answer: B

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Question 7

The half-life of a radioactive subs\tance is 5.0 days. If 100 g of the subs\tance is initially present, how much will remain after 20 days?

Correct A. 12.5 g

B. 25.0 g

C. 50.0 g

D. 100 g

Correct Answer: A

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Question 8

A 2.00 M solution of HCl is mixed with a 2.00 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 9

A 1.00 M solution of K2Cr2O7 is mixed with a 1.00 M solution of FeSO4. What is the concentration of Cr3+ ions in the resulting solution?

A. 0.500 M

B. 0.667 M

Correct C. 0.750 M

D. 1.00 M

Correct Answer: C

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Question 10

A 0.500 M solution of NaOH is mixed with a 0.500 M solution of HCl. What is the concentration of NaCl that remains in the solution?

A. 0.250 M

Correct B. 0.333 M

C. 0.500 M

D. 0.667 M

Correct Answer: B

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Question 11

The reaction between chlorine gas and sodium hydroxide solution produces a compound that is a strong base. What is the chemical formula of this compound?

A. NaClO

B. NaOH

C. NaCl

Correct D. NaOCl

Correct Answer: D

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Question 12

A 2.5 g sample of a non-metallic oxide is heated in a crucible until it decomposes completely. The mass of the residue is 1.8 g. What is the percentage of the original sample that decomposed?

Correct A. 72%

B. 60%

C. 80%

D. 90%

Correct Answer: A

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Question 13

A solution of sodium chloride is prepared by dissolving 35.5 g of NaCl in 250 mL of water. What is the molarity of the solution?

A. 0.5 M

Correct B. 1.0 M

C. 1.5 M

D. 2.0 M

Correct Answer: B

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Question 14

A mixture of 2.0 g of an organic compound and 1.5 g of an inorganic compound is heated in a crucible until the organic compound is completely decomposed. The mass of the residue is 2.2 g. What is the percentage of the original mixture that was inorganic?

A. 60%

B. 50%

Correct C. 40%

D. 30%

Correct Answer: C

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Question 15

A 5.0 g sample of a metal oxide is heated in a crucible until it decomposes completely. The mass of the residue is 3.2 g. What is the percentage of the original sample that decomposed?

A. 36%

B. 40%

Correct C. 44%

D. 48%

Correct Answer: C

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Question 16

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) at the same temperature.

Correct A. -110.5 kJ/mol

B. -393.5 kJ/mol

C. -283.0 kJ/mol

D. -197.7 kJ/mol

Correct Answer: A

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Question 17

A 2.50 L flask contains 0.250 mol of an ideal gas at 298 K. Calculate the pressure of the gas in the flask.

A. 1.01 x 10^2 kPa

Correct B. 2.01 x 10^2 kPa

C. 3.01 x 10^2 kPa

D. 4.01 x 10^2 kPa

Correct Answer: B

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Question 18

The s\tandard enthalpy of combustion of methane is -890.3 kJ/mol. Calculate the s\tandard enthalpy of formation of methane at 298 K.

A. -50.5 kJ/mol

B. -74.8 kJ/mol

Correct C. -890.3 kJ/mol

D. -110.5 kJ/mol

Correct Answer: C

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Question 19

A 1.00 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the s\tandard enthalpy of formation of the gas.

Correct A. -393.5 kJ/mol

B. -110.5 kJ/mol

C. -283.0 kJ/mol

D. -197.7 kJ/mol

Correct Answer: A

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Question 20

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) at 298 K.

Correct A. -110.5 kJ/mol

B. -393.5 kJ/mol

C. -283.0 kJ/mol

D. -197.7 kJ/mol

Correct Answer: A

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Question 21

Determine the pH of a 0.1 M solution of HCl at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the temperature dep\endence of the dissociation cons\tant is given by the equation \( \log_{10} K = -\frac{1000}{T} + 1.5 \).

A. 3

B. 4

C. 5

Correct D. 6

Correct Answer: D

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Question 22

A 2.5 g sample of a metal oxide is dissolved in 50 mL of 0.5 M HCl. The resulting solution is then titrated with 0.1 M NaOH. If the volume of NaOH required to reach the equivalence point is 25 mL, what is the molar mass of the metal oxide?

A. 50

B. 75

Correct C. 100

D. 150

Correct Answer: C

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Question 23

A 1.0 L sample of a gas at 25°C and 1 atm is compressed to 0.5 L at the same temperature. What is the new pressure of the gas?

A. 2

B. 3

C. 4

Correct D. 5

Correct Answer: D

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Question 24

A 50 mL sample of a 0.1 M solution of NaOH is mixed with 50 mL of a 0.1 M solution of HCl. What is the pH of the resulting solution?

Correct A. 7

B. 8

C. 9

D. 10

Correct Answer: A

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Question 25

A 2.0 g sample of a metal is heated in a crucible until it melts. The resulting liquid is then cooled and solidified. What is the type of crystal structure that the metal will exhibit?

A. Face-Centered Cubic

B. Body-Centered Cubic

Correct C. Hexagonal Close-Packed

D. Diamond Cubic

Correct Answer: C

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