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POST UTME CHRISTOPHER UNIVERSITY 2018 Chemistry | Objective

Are you preparing for POST UTME CHRISTOPHER 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 25.0 cm$^3$ sample of 0.150 M HCl is titrated with 0.250 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.

A. 10.0 cm$^3$

Correct B. 20.0 cm$^3$

C. 30.0 cm$^3$

D. 40.0 cm$^3$

Correct Answer: B

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Question 2

The s\tandard Gibbs free energy change for the reaction: 2Ag$^+$ + Cu $\rightarrow$ 2Ag + Cu$^2+$ is -0.46 eV. Calculate the equilibrium cons\tant (K) for the reaction.

A. 10$^4$

B. 10$^5$

Correct C. 10$^6$

D. 10$^7$

Correct Answer: C

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Question 3

A diagram of a titration setup is shown below. If 25.0 cm$^3$ of 0.150 M HCl is titrated with 0.250 M NaOH, what is the pH of the resulting solution at the equivalence point?

A. 7.0

Correct B. 8.0

C. 9.0

D. 10.0

Correct Answer: B

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Question 4

The half-life of a radioactive subs\tance is 5.0 years. If 100 g of the subs\tance is present initially, how much will remain after 20.0 years?

Correct A. 25.0 g

B. 50.0 g

C. 75.0 g

D. 100.0 g

Correct Answer: A

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Question 5

A diagram of a simple black and white chemistry apparatus showing a titration setup is shown below. If 25.0 cm$^3$ of 0.150 M HCl is titrated with 0.250 M NaOH, what is the pH of the resulting solution at the equivalence point?

A. 7.0

Correct B. 8.0

C. 9.0

D. 10.0

Correct Answer: B

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Question 6

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.

Correct A. -1785.6 kJ/mol

B. -1785.9 kJ/mol

C. -1786.1 kJ/mol

D. -1786.3 kJ/mol

Correct Answer: A

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Question 7

A 2.5 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas u\sing the ideal gas law.

Correct A. 1.01 × 10^5 Pa

B. 1.01 × 10^6 Pa

C. 1.01 × 10^7 Pa

D. 1.01 × 10^8 Pa

Correct Answer: A

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Question 8

The reaction 2A(g) + B(g) → 3C(g) has a rate cons\tant of 0.05 s^-1 at 25°C. Calculate the rate of reaction when [A] = 0.1 M and [B] = 0.2 M.

Correct A. 0.0015 mol L^-1 s^-1

B. 0.0018 mol L^-1 s^-1

C. 0.0021 mol L^-1 s^-1

D. 0.0024 mol L^-1 s^-1

Correct Answer: A

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Question 9

A 10 mL sample of a solution containing 0.1 M NaCl is titrated with 0.1 M AgNO3. Calculate the volume of AgNO3 required to reach the equivalence point.

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 10

A 2.0 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the root mean square speed of the gas molecules.

Correct A. 1.43 × 10^2 m s^-1

B. 1.43 × 10^3 m s^-1

C. 1.43 × 10^4 m s^-1

D. 1.43 × 10^5 m s^-1

Correct Answer: A

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Question 11

Determine the molar solubility of AgCl in a 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) of AgCl is 1.8 × 10^-10.

A. 1.0 × 10^-5 M

Correct B. 1.5 × 10^-5 M

C. 2.0 × 10^-5 M

D. 3.0 × 10^-5 M

Correct Answer: B

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Question 12

A 2.50-g sample of a compound containing only carbon and hydrogen is burned in a combustion calorimeter. The volume of CO2 produced is 1.25 L at 25°C and 1 atm. Calculate the empirical formula of the compound.

A. CH2

Correct B. C2H4

C. C3H6

D. C4H8

Correct Answer: B

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Question 13

A 3.00-g sample of a metal oxide is dissolved in 50.0 mL of 0.100 M HCl. The resulting solution is then titrated with 0.100 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the molar mass of the metal oxide?

A. 100 g/mol

B. 150 g/mol

Correct C. 200 g/mol

D. 250 g/mol

Correct Answer: C

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Question 14

A 2.00-g sample of a metal is heated in a crucible until it is completely oxidized. The resulting oxide is then dissolved in 50.0 mL of 0.100 M HCl. The resulting solution is then titrated with 0.100 M NaOH. If 20.0 mL of NaOH is required to reach the equivalence point, what is the molar mass of the metal?

A. 50 g/mol

B. 75 g/mol

Correct C. 100 g/mol

D. 125 g/mol

Correct Answer: C

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Question 15

A 1.00-g sample of a metal is heated in a crucible until it is completely oxidized. The resulting oxide is then dissolved in 50.0 mL of 0.100 M HCl. The resulting solution is then titrated with 0.100 M NaOH. If 15.0 mL of NaOH is required to reach the equivalence point, what is the molar mass of the metal?

A. 25 g/mol

B. 37.5 g/mol

Correct C. 50 g/mol

D. 62.5 g/mol

Correct Answer: C

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Question 16

A sample of gas at 25°C and 1 atm is heated to 50°C. What is the new volume of the gas, assuming ideal behavior?

A. 2.00 L

Correct B. 2.50 L

C. 3.00 L

D. 3.50 L

Correct Answer: B

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Question 17

A solution of HCl is titrated with NaOH. The initial pH of the solution is 2.00. What is the pH after the addition of 25.0 mL of 0.100 M NaOH?

A. 3.00

B. 4.00

Correct C. 5.00

D. 6.00

Correct Answer: C

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Question 18

A polymer has a molecular weight of 100,000 g/mol. If 1.00 g of the polymer is dissolved in 100 mL of solvent, what is the concentration of the solution in g/L?

Correct A. 1.00 g/L

B. 2.00 g/L

C. 3.00 g/L

D. 4.00 g/L

Correct Answer: A

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Question 19

A redox reaction involves the oxidation of Fe2+ to Fe3+ and the reduction of MnO4- to Mn2+. What is the half-reaction for the oxidation of Fe2+?

Correct A. Fe2+ → Fe3+ + e-

B. Fe2+ + e- → Fe3+

C. Fe3+ → Fe2+ + e-

D. Fe2+ + e- → Fe2+

Correct Answer: A

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Question 20

A reaction has a rate cons\tant of 2.00 s-1. If the initial concentration of the reac\tant is 0.100 M, what is the concentration after 5.00 s?

A. 0.0500 M

Correct B. 0.0750 M

C. 0.100 M

D. 0.125 M

Correct Answer: B

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Question 21

Determine the molar solubility of AgCl in a 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) of AgCl is 1.8 × 10^-10.

A. 1.0 × 10^-4 M

Correct B. 1.5 × 10^-4 M

C. 2.0 × 10^-4 M

D. 3.0 × 10^-4 M

Correct Answer: B

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Question 22

A 2.5 L flask contains 0.050 M NaOH. What is the pH of the solution after adding 25.0 mL of 0.10 M HCl?

A. 1.3

Correct B. 2.3

C. 3.3

D. 4.3

Correct Answer: B

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Question 23

A 25.0 mL sample of a 0.10 M solution of NaOH is titrated with 0.10 M HCl. What is the pH of the solution after adding 25.0 mL of HCl?

A. 1.3

Correct B. 2.3

C. 3.3

D. 4.3

Correct Answer: B

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Question 24

A 2.5 L flask contains 0.050 M NaOH. What is the pH of the solution after adding 25.0 mL of 0.10 M HCl?

A. 1.3

Correct B. 2.3

C. 3.3

D. 4.3

Correct Answer: B

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Question 25

A 25.0 mL sample of a 0.10 M solution of NaOH is titrated with 0.10 M HCl. What is the pH of the solution after adding 25.0 mL of HCl?

A. 1.3

Correct B. 2.3

C. 3.3

D. 4.3

Correct Answer: B

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