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POST UTME UNIBEN 2024 Chemistry | Objective

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Question 1

A 0.1 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 100 mL of water. What is the concentration of the solution in mol/L?

A. 0.05 M

Correct B. 0.1 M

C. 0.2 M

D. 0.5 M

Correct Answer: B

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Question 2

The diagram below shows a titration setup. What is the purpose of the burette?

Correct A. To measure the volume of the titrant

B. To measure the volume of the analyte

C. To mix the titrant and analyte

D. To heat the solution

Correct Answer: A

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Question 3

A 2 M solution of HCl is prepared by dissolving 40 g of HCl in 100 mL of water. What is the concentration of the solution in mol/L?

A. 1 M

Correct B. 2 M

C. 4 M

D. 8 M

Correct Answer: B

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Question 4

The diagram below shows a circuit. What is the purpose of the resistor?

A. To reduce the voltage

Correct B. To reduce the current

C. To increase the voltage

D. To increase the current

Correct Answer: B

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Question 5

A 0.1 M solution of NaOH is prepared by dissolving 2 g of NaOH in 100 mL of water. What is the concentration of the solution in mol/L?

A. 0.05 M

Correct B. 0.1 M

C. 0.2 M

D. 0.5 M

Correct Answer: B

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Question 6

In the reaction 2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(s), what is the oxidation state of aluminum (Al) in the product Al2O3?

A. 0

Correct B. +3

C. +1

D. -3

Correct Answer: B

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Question 7

A 2.5 M solution of HCl is mixed with a 1.5 M solution of NaOH. What is the concentration of the resulting solution?

Correct A. 2.0 M

B. 1.5 M

C. 3.0 M

D. 4.0 M

Correct Answer: A

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Question 8

The half-life of a radioactive subs\tance is 10 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 20 years?

A. 50 g

B. 25 g

Correct C. 12.5 g

D. 6.25 g

Correct Answer: C

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Question 9

A 1.0 M solution of H2SO4 is mixed with a 2.0 M solution of NaOH. What is the concentration of the resulting solution?

A. 1.0 M

Correct B. 2.0 M

C. 3.0 M

D. 4.0 M

Correct Answer: B

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Question 10

The diagram below shows a titration setup. What is the purpose of the burette?

Correct A. To measure the volume of the solution

B. To measure the concentration of the solution

C. To mix the solutions

D. To filter the solution

Correct Answer: A

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Question 11

A polymer is formed by the condensation reaction between two monomers, A and B. If the molecular weight of A is 100 g/mol and the molecular weight of B is 150 g/mol, and the reaction produces 2 moles of water for every mole of polymer formed, what is the average molecular weight of the polymer formed?

A. 175 g/mol

B. 200 g/mol

Correct C. 225 g/mol

D. 250 g/mol

Correct Answer: C

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Question 12

A solution of 0.1 M HCl is mixed with a solution of 0.2 M NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?

A. 0.05 M

B. 0.1 M

Correct C. 0.15 M

D. 0.2 M

Correct Answer: C

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Question 13

A cell consists of a zinc anode and a copper cathode. If the cell is connected to a 10 V power source, what is the current flowing through the cell?

A. 0.5 A

Correct B. 1 A

C. 2 A

D. 5 A

Correct Answer: B

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Question 14

A reaction is first-order with respect to the reac\tant A. If the initial concentration of A is 0.1 M and the rate cons\tant is 0.01 min^-1, what is the concentration of A after 10 minutes?

Correct A. 0.01 M

B. 0.05 M

C. 0.1 M

D. 0.2 M

Correct Answer: A

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Question 15

A solution of 0.1 M HCl is mixed with a solution of 0.2 M NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?

A. 0.05 M

B. 0.1 M

Correct C. 0.15 M

D. 0.2 M

Correct Answer: C

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Question 16

Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol, and ΔHf(C(s)) = 0 kJ/mol.

Correct A. -1206.60 kJ/mol

B. -1206.19 kJ/mol

C. -1207.19 kJ/mol

D. -1207.60 kJ/mol

Correct Answer: A

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Question 17

A 2.50 M solution of HCl is titrated with 1.00 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the concentration of HCl?

A. 1.00 M

Correct B. 1.25 M

C. 1.50 M

D. 2.00 M

Correct Answer: B

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Question 18

The reaction 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant of 1.50 × 10^\( -3 \) s^\( -1 \) at 298 K. What is the rate cons\tant at 323 K?

A. 2.50 × 10^\( -3 \) s^\( -1 \)

B. 3.00 × 10^\( -3 \) s^\( -1 \)

Correct C. 3.50 × 10^\( -3 \) s^\( -1 \)

D. 4.00 × 10^\( -3 \) s^\( -1 \)

Correct Answer: C

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Question 19

A 0.100 M solution of NaOH is titrated with 0.100 M HCl. If 25.0 mL of HCl is required to reach the equivalence point, what is the pH of the resulting solution?

A. 7.00

B. 7.25

Correct C. 7.50

D. 8.00

Correct Answer: C

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Question 20

A 1.00 M solution of H2SO4 is titrated with 1.00 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the concentration of H2SO4?

A. 0.500 M

B. 0.750 M

Correct C. 1.00 M

D. 1.25 M

Correct Answer: C

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Question 21

A solution of 0.1 M NaCl is mixed with a solution of 0.1 M NaOH. What is the concentration of the resulting solution?

A. 0.1 M

Correct B. 0.05 M

C. 0.2 M

D. 0.15 M

Correct Answer: B

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Question 22

The rate cons\tant for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?

Correct A. 0.01 M

B. 0.05 M

C. 0.1 M

D. 0.2 M

Correct Answer: A

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Question 23

A sample of 2.0 g of an organic compound containing only carbon and hydrogen is analyzed by combustion. The amount of CO2 produced is 1.2 g, and the amount of H2O produced is 0.8 g. What is the empirical formula of the compound?

Correct A. C2H4

B. C3H6

C. C4H8

D. C5H10

Correct Answer: A

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Question 24

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

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 25

A sample of 1.0 g of a non-metallic element is analyzed by combustion. The amount of O2 consumed is 0.8 g, and the amount of CO2 produced is 0.2 g. What is the empirical formula of the element?

A. O2

Correct B. S8

C. Cl2

D. F2

Correct Answer: B

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