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POST UTME ESUT 2021 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 2.5 g sample of an unknown metal is heated in a crucible until it melts. The mass of the crucible and metal is 2.8 g. The mass of the crucible alone is 2.2 g. What is the density of the metal?

A. 2.5 g/cm^3

Correct B. 3.5 g/cm^3

C. 4.5 g/cm^3

D. 5.5 g/cm^3

Correct Answer: B

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Question 3

A solution of 0.1 M NaOH is titrated with 0.1 M HCl. What is the pH of the solution after 25 mL of HCl has been added?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 4

A 2.5 g sample of an unknown metal is heated in a crucible until it melts. The mass of the crucible and metal is 2.8 g. The mass of the crucible alone is 2.2 g. What is the density of the metal?

A. 2.5 g/cm^3

Correct B. 3.5 g/cm^3

C. 4.5 g/cm^3

D. 5.5 g/cm^3

Correct Answer: B

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Question 5

A solution of 0.1 M NaOH is titrated with 0.1 M HCl. What is the pH of the solution after 25 mL of HCl has been added?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 6

Determine the number of moles of $\text{CO}_2$ produced when 2.50 g of $\text{CaCO}_3$ is decomposed at cons\tant pressure.

A. 0.0250 mol

Correct B. 0.0500 mol

C. 0.100 mol

D. 0.200 mol

Correct Answer: B

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Question 7

A 0.500 M solution of $\text{H}_2\text{SO}_4$ is titrated with 0.500 M $\text{NaOH}$. What is the pH of the solution after 25.0 mL of $\text{NaOH}$ has been added?

A. 1.00

B. 2.00

Correct C. 3.00

D. 4.00

Correct Answer: C

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Question 8

A 2.00 g sample of a polymer is dissolved in 100.0 mL of solvent. The osmotic pressure of the solution is 2.50 atm at 25.0°C. What is the molar mass of the polymer?

A. 100.0 g/mol

B. 200.0 g/mol

Correct C. 500.0 g/mol

D. 1000.0 g/mol

Correct Answer: C

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Question 9

A 1.00 M solution of $\text{HCl}$ is titrated with 1.00 M $\text{NaOH}$. What is the pH of the solution after 50.0 mL of $\text{NaOH}$ has been added?

A. 1.00

B. 2.00

C. 3.00

Correct D. 4.00

Correct Answer: D

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Question 10

A 0.500 g sample of a subs\tance is dissolved in 100.0 mL of solvent. The boiling point elevation of the solution is 0.500°C. What is the molar mass of the subs\tance?

A. 100.0 g/mol

B. 200.0 g/mol

Correct C. 500.0 g/mol

D. 1000.0 g/mol

Correct Answer: C

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Question 11

Determine the number of moles of $CO_2$ produced when 2.5 g of $CaC_2$ is heated in a stream of $CO_2$ gas at $25^circ C$ and 1 atm.

A. 0.05 mol

Correct B. 0.10 mol

C. 0.15 mol

D. 0.20 mol

Correct Answer: B

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Question 12

A solution contains $0.10$ mol of $NaCl$ per liter. What is the concentration of $Na^+$ ions in the solution?

A. 0.05 M

Correct B. 0.10 M

C. 0.15 M

D. 0.20 M

Correct Answer: B

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Question 13

A $1.0$ L solution contains $0.50$ mol of $H_2SO_4$. What is the concentration of $H^+$ ions in the solution?

A. 0.25 M

Correct B. 0.50 M

C. 0.75 M

D. 1.0 M

Correct Answer: B

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Question 14

A $2.0$ L solution contains $1.0$ mol of $NaOH$. What is the concentration of $OH^-$ ions in the solution?

A. 0.25 M

Correct B. 0.50 M

C. 0.75 M

D. 1.0 M

Correct Answer: B

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Question 15

A $1.0$ L solution contains $0.50$ mol of $HCl$. What is the concentration of $H^+$ ions in the solution?

A. 0.25 M

Correct B. 0.50 M

C. 0.75 M

D. 1.0 M

Correct Answer: B

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Question 16

The reaction between sodium hydroxide and acetic acid is represented by the equation: CH3COOH + NaOH → CH3COONa + H2O. If 25 mL of 0.5 M acetic acid is mixed with 25 mL of 0.5 M sodium hydroxide, what is the concentration of the resulting solution?

A. 0.25 M

B. 0.5 M

Correct C. 1.0 M

D. 1.5 M

Correct Answer: C

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Question 17

A 2.5 g sample of a polymer is dissolved in 50 mL of a solvent. The solution is then diluted to 100 mL. What is the concentration of the polymer solution in g/L?

A. 0.025 g/L

Correct B. 0.05 g/L

C. 0.1 g/L

D. 0.2 g/L

Correct Answer: B

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Question 18

A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of HCl is required to reach the equivalence point, what is the volume of NaOH required to reach the equivalence point?

Correct A. 20 mL

B. 30 mL

C. 40 mL

D. 50 mL

Correct Answer: A

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Question 19

A 2.5 g sample of a metal is heated in a crucible until it reaches a temperature of 1000°C. If the metal has a specific heat capacity of 0.1 J/g°C, what is the energy required to heat the metal to 1000°C?

A. 250 J

B. 500 J

C. 750 J

Correct D. 1000 J

Correct Answer: D

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Question 20

A 0.5 M solution of a weak acid is titrated with 0.5 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the pH of the resulting solution?

A. 7

Correct B. 8

C. 9

D. 10

Correct Answer: B

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Question 21

Determine the number of moles of CO2 produced when 2.5 g of calcium carbonate (CaCO3) is decomposed completely in a reaction with hydrochloric acid (HCl). The molar mass of CaCO3 is 100.09 g/mol, and the molar mass of CO2 is 44.01 g/mol. The balanced chemical equation for the reaction is: CaCO3 + 2HCl -> CaCl2 + CO2 + H2O.

A. 0.056 mol

Correct B. 0.0565 mol

C. 0.057 mol

D. 0.0575 mol

Correct Answer: B

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Question 22

A polymer is made from a monomer with the molecular formula C5H8. If the polymer has a degree of polymerization of 500, what is the molar mass of the polymer?

A. 2500 g/mol

B. 25000 g/mol

Correct C. 250000 g/mol

D. 2500000 g/mol

Correct Answer: C

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Question 23

A 2.0 M solution of hydrochloric acid (HCl) is mixed with a 1.0 M solution of sodium hydroxide (NaOH). If 50 mL of the HCl solution is mixed with 50 mL of the NaOH solution, what is the concentration of the resulting 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 24

A 10.0 g sample of an unknown hydrocarbon is burned in a combustion apparatus. The volume of carbon dioxide gas produced is 22.5 L at 25°C and 1 atm. What is the empirical formula of the hydrocarbon?

A. C2H4

Correct B. C3H6

C. C4H8

D. C5H10

Correct Answer: B

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Question 25

A 2.0 M solution of sodium hydroxide (NaOH) is mixed with a 1.0 M solution of hydrochloric acid (HCl). If 50 mL of the NaOH solution is mixed with 50 mL of the HCl solution, what is the concentration of the resulting 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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