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POST UTME COVENANT UNIVERSITY 2018 Chemistry | Objective

Are you preparing for POST UTME COVENANT UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2018 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

A 0.1 M solution of a weak acid HA is titrated with 0.1 M NaOH. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the acid.

A. 0.1 M

Correct B. 0.05 M

C. 0.01 M

D. 0.005 M

Correct Answer: B

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Question 2

A metal M reacts with chlorine gas to form a white solid MX. If 2.5 g of M is heated in a stream of Cl2, 3.2 g of MX is produced. Calculate the empirical formula of MX.

A. MCl2

Correct B. MCl3

C. MCl4

D. MCl5

Correct Answer: B

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Question 3

A 2.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. If 50 mL of the NaOH solution is added to 100 mL of the HCl solution, 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 4

A 0.1 M solution of a weak base B is titrated with 0.1 M HCl. At the equivalence point, the pH of the solution is 7. Calculate the initial concentration of the base.

A. 0.1 M

Correct B. 0.05 M

C. 0.01 M

D. 0.005 M

Correct Answer: B

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Question 5

A metal M reacts with oxygen gas to form a brown solid MO. If 2.5 g of M is heated in a stream of O2, 4.2 g of MO is produced. Calculate the empirical formula of MO.

A. M2O3

Correct B. MO

C. M2O

D. M3O4

Correct Answer: B

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Question 6

A polymer is formed by the condensation reaction between two monomers, A and B. If the molecular weight of the polymer is 200 g/mol and the molecular weights of the monomers are 50 g/mol and 100 g/mol, respectively, what is the ratio of the number of moles of monomer A to the number of moles of monomer B in the polymer?

A. 1:2

B. 2:1

Correct C. 1:1

D. 3:2

Correct Answer: C

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Question 7

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. What is the s\tandard enthalpy of formation of CH4(g)?

Correct A. -74.8 kJ/mol

B. -74.5 kJ/mol

C. -74.2 kJ/mol

D. -75.1 kJ/mol

Correct Answer: A

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Question 8

A 2.50 M solution of NaOH is titrated with a 1.00 M solution of HCl. What is the pH of the solution after 25.0 mL of HCl has been added?

A. 2.00

Correct B. 3.00

C. 4.00

D. 5.00

Correct Answer: B

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Question 9

A sample of nitrogen gas occupies a volume of 2.50 L at a pressure of 1.00 atm and a temperature of 298 K. What is the volume of the gas at a pressure of 2.00 atm and a temperature of 298 K?

Correct A. 1.25 L

B. 2.50 L

C. 3.75 L

D. 5.00 L

Correct Answer: A

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Question 10

A 1.00 M solution of H2SO4 is titrated with a 1.00 M solution of NaOH. What is the pH of the solution after 25.0 mL of NaOH has been added?

A. 2.00

B. 3.00

Correct C. 4.00

D. 5.00

Correct Answer: C

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Question 11

The atomic radius of an element is 100 pm. If the element is in its ground state, what is the expected value of its atomic radius when it is in its first excited state?

Correct A. 120 pm

B. 80 pm

C. 90 pm

D. 110 pm

Correct Answer: A

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Question 12

A 0.1 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 13

The half-life of a radioactive subs\tance is 5 years. If the initial activity is 1000 Bq, what is the activity after 10 years?

Correct A. 100 Bq

B. 200 Bq

C. 500 Bq

D. 1000 Bq

Correct Answer: A

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Question 14

A metal rod of length 1 m and cross-sectional area 0.01 m^2 is subjected to a tensile force of 100 N. What is the stress on the rod?

Correct A. 10 MPa

B. 20 MPa

C. 30 MPa

D. 40 MPa

Correct Answer: A

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Question 15

A 1 M solution of HCl is titrated with 1 M NaOH. What is the pH of the solution after 50 mL of NaOH has been added?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 16

Determine the oxidation state of the metal in the complex [Cr(H2O)5Cl]Cl2.

A. +2

Correct B. +3

C. +6

D. +7

Correct Answer: B

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Question 17

A 2.5g sample of an organic compound containing only carbon, hydrogen, and oxygen is analyzed by combustion. The amount of carbon dioxide produced is 1.8g. The amount of water produced is 0.9g. Calculate the empirical formula of the compound.

A. C2H4O

Correct B. C3H6O2

C. C4H8O3

D. C5H10O4

Correct Answer: B

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Question 18

A solution containing 0.1M NaCl is mixed with a solution containing 0.1M AgNO3. The resulting precipitate is filtered and dried. Calculate the mass of the precipitate.

A. 0.01g

B. 0.02g

Correct C. 0.03g

D. 0.04g

Correct Answer: C

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Question 19

A 10g sample of a metal is electrolyzed u\sing a current of 5A for 10 minutes. The mass of the metal deposited is 8g. Calculate the molar mass of the metal.

A. 50g/mol

B. 60g/mol

Correct C. 70g/mol

D. 80g/mol

Correct Answer: C

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Question 20

A 2.0M solution of HCl is mixed with a 2.0M solution of NaOH. The resulting solution is titrated with a 1.0M solution of HCl. Calculate the volume of the 1.0M HCl solution required to reach the equivalence point.

A. 20mL

Correct B. 30mL

C. 40mL

D. 50mL

Correct Answer: B

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Question 21

At 298 K, the s\tandard enthalpy change \( ΔH^circ \) for the reaction C(s) + O2(g) → CO2(g) is -393.5 kJ/mol. Calculate the s\tandard entropy change \( ΔS^circ \) for this reaction.

Correct A. -134.3 J/mol·K

B. -134.5 J/mol·K

C. -134.7 J/mol·K

D. -134.9 J/mol·K

Correct Answer: A

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Question 22

A 2.50 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.

Correct A. 1.01 × 10^5 Pa

B. 2.02 × 10^5 Pa

C. 3.03 × 10^5 Pa

D. 4.04 × 10^5 Pa

Correct Answer: A

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Question 23

The s\tandard enthalpy of formation \( ΔH^circ_f \) for CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation for C(s) u\sing Hess's law.

Correct A. -393.5 kJ/mol

B. -394.5 kJ/mol

C. -395.5 kJ/mol

D. -396.5 kJ/mol

Correct Answer: A

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Question 24

A 1.00 L flask contains 0.500 mol of an ideal gas at 298 K. Calculate the volume of the gas at 300 K u\sing Charles's law.

Correct A. 1.01 L

B. 1.02 L

C. 1.03 L

D. 1.04 L

Correct Answer: A

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Question 25

The s\tandard enthalpy of combustion \( ΔH^circ_c \) for C(s) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion for CO2(g) u\sing Hess's law.

Correct A. -393.5 kJ/mol

B. -394.5 kJ/mol

C. -395.5 kJ/mol

D. -396.5 kJ/mol

Correct Answer: A

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