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POST UTME CALEB UNIVERSITY 2017 Chemistry | Objective

Are you preparing for POST UTME CALEB UNIVERSITY exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2017 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1

The rate cons\tant (k) of a first-order reaction is given by the equation \( k = Ae^{-E_a/RT} \). If the activation energy \( E_a \) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/\( mol*K \), and the temperature (T) is 300 K, calculate the value of k when A = 1.0 s^-1.

Correct A. 0.0001 s^-1

B. 0.001 s^-1

C. 0.01 s^-1

D. 0.1 s^-1

Correct Answer: A

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Question 2

A 0.100 M solution of NaCl is prepared by dissolving 10.0 g of NaCl in 100 mL of water. What is the concentration of Na+ ions in the solution?

A. 0.050 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 3

A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M HCl is required to reach the equivalence point, what is the concentration of the NaOH solution?

A. 0.050 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 4

A 1.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 23.8 mmHg, what is the partial pressure of the gas?

Correct A. 0.977 atm

B. 0.983 atm

C. 0.989 atm

D. 0.995 atm

Correct Answer: A

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Question 5

A 2.00 g sample of a polymer is dissolved in 100 mL of solvent. If the polymer has a molecular weight of 100,000 g/mol, what is the concentration of the polymer solution?

A. 0.02 g/mL

Correct B. 0.05 g/mL

C. 0.10 g/mL

D. 0.20 g/mL

Correct Answer: B

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Question 6

The reaction of zinc metal with copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). What is the oxidation state of copper in the product Cu(s)?

A. 0

B. +1

Correct C. +2

D. -1

Correct Answer: C

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Question 7

A 25.0 mL sample of 0.100 M NaOH is titrated with 0.100 M HCl. Calculate the number of moles of HCl required to reach the equivalence point.

A. 0.0025

Correct B. 0.0050

C. 0.0075

D. 0.0100

Correct Answer: B

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Question 8

The atomic radius of an element is 100 pm. If the element has an electron configuration of [Ar] 4s^2 3d^5, what is the expected oxidation state of the element in its compounds?

A. +2

Correct B. +3

C. +4

D. +5

Correct Answer: B

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Question 9

A solution containing 0.500 M NaCl is prepared by dissolving 25.0 g of NaCl in 1.00 L of water. What is the concentration of Cl^- ions in the solution?

A. 0.250 M

Correct B. 0.500 M

C. 0.750 M

D. 1.00 M

Correct Answer: B

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Question 10

A 2.00 L sample of 0.100 M H2SO4 is titrated with 0.100 M NaOH. Calculate the number of moles of NaOH required to reach the equivalence point.

A. 0.0020

Correct B. 0.0040

C. 0.0060

D. 0.0080

Correct Answer: B

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Question 11

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, ΔHf(C(s)) = 0 kJ/mol.

Correct A. -1206.60 kJ/mol

B. -1206.10 kJ/mol

C. -1207.10 kJ/mol

D. -1207.60 kJ/mol

Correct Answer: A

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Question 12

A sample of nitrogen gas is collected over water at 25°C and 1 atm. If the partial pressure of water vapor is 0.0313 atm, what is the mole \fraction of nitrogen gas?

Correct A. 0.969

B. 0.971

C. 0.973

D. 0.975

Correct Answer: A

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Question 13

The half-life of a radioactive subs\tance is 5.27 years. If 100 g of the subs\tance initially decays to 50 g, how many years will it take for the subs\tance to decay to 25 g?

A. 10.54 years

Correct B. 10.64 years

C. 10.74 years

D. 10.84 years

Correct Answer: B

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Question 14

A 2.50 L sample of a gas at 25°C and 1 atm is collected over water at 25°C. If the partial pressure of water vapor is 0.0313 atm, what is the mole \fraction of the gas?

Correct A. 0.969

B. 0.971

C. 0.973

D. 0.975

Correct Answer: A

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Question 15

A 2.50 L sample of a gas at 25°C and 1 atm is collected over water at 25°C. If the partial pressure of water vapor is 0.0313 atm, what is the mole \fraction of the gas?

Correct A. 0.969

B. 0.971

C. 0.973

D. 0.975

Correct Answer: A

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Question 16

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CaCO3(s) u\sing the following reaction: CaO(s) + CO2(g) → CaCO3(s).

A. -1781.5 kJ/mol

B. -1781.0 kJ/mol

C. -1781.0 kJ/mol

Correct D. -1781.5 kJ/mol

Correct Answer: D

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Question 17

The half-reaction for the reduction of MnO4- is: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O. What is the s\tandard reduction potential of MnO4-?

A. +1.51 V

B. +1.51 V

C. +1.51 V

Correct D. +1.51 V

Correct Answer: D

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Question 18

A 2.50 M solution of HCl is mixed with a 1.50 M solution of NaOH. What is the concentration of the resulting solution?

A. 1.00 M

B. 1.00 M

C. 1.00 M

Correct D. 1.00 M

Correct Answer: D

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Question 19

The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of formation of NH4Cl(s) u\sing the following reaction: NH3(g) + HCl(g) → NH4Cl(s).

A. -365.5 kJ/mol

B. -365.5 kJ/mol

C. -365.5 kJ/mol

Correct D. -365.5 kJ/mol

Correct Answer: D

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Question 20

The half-reaction for the oxidation of Fe2+ is: Fe2+ → Fe3+ + e-. What is the s\tandard oxidation potential of Fe2+?

A. +0.77 V

B. +0.77 V

C. +0.77 V

Correct D. +0.77 V

Correct Answer: D

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Question 21

A 1.00 M solution of H2SO4 is mixed with a 2.00 M solution of NaOH. What is the concentration of the resulting solution?

A. 1.00 M

B. 1.00 M

C. 1.00 M

Correct D. 1.00 M

Correct Answer: D

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Question 22

The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) u\sing the following reaction: 2CO(g) + 4H2(g) → CH4(g) + 2H2O(g).

A. -74.8 kJ/mol

B. -74.8 kJ/mol

C. -74.8 kJ/mol

Correct D. -74.8 kJ/mol

Correct Answer: D

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Question 23

The half-reaction for the reduction of Cr2O72- is: Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O. What is the s\tandard reduction potential of Cr2O72-?

A. +1.33 V

B. +1.33 V

C. +1.33 V

Correct D. +1.33 V

Correct Answer: D

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Question 24

A 2.00 M solution of HNO3 is mixed with a 1.00 M solution of NaOH. What is the concentration of the resulting solution?

A. 1.00 M

B. 1.00 M

C. 1.00 M

D. 1.00 M

Correct Answer: VIEW ANSWER

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Question 25

Calculate the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that the s\tandard enthalpy of formation for Al2O3(s) is -1675.7 kJ/mol, the s\tandard enthalpy of formation for Fe2O3(s) is -826.4 kJ/mol, and the s\tandard enthalpy of formation for Fe(s) is 0 kJ/mol.

Correct A. -1024.1 kJ/mol

B. -1024.2 kJ/mol

C. -1024.3 kJ/mol

D. -1024.4 kJ/mol

Correct Answer: A

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