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POST UTME RHEMA UNIVERSITY 2017 Chemistry | Objective

Are you preparing for POST UTME RHEMA 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

A sample of an ideal gas at 25°C and 1 atm is heated to 50°C at cons\tant pressure. Calculate the new volume of the gas, given that the initial volume is 2.5 L.

A. 3.125 L

Correct B. 4.166 L

C. 5.208 L

D. 6.25 L

Correct Answer: B

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Question 2

The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance initially decays to 50 g after 5 years, what is the decay cons\tant (λ) of the subs\tance?

Correct A. 0.139 yr^{-1}

B. 0.139 yr^{-1}

C. 0.139 yr^{-1}

D. 0.139 yr^{-1}

Correct Answer: A

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Question 3

A 2.0 M solution of HCl is mixed with a 2.0 M solution of NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?

A. 1.0 M HCl

B. 1.0 M NaOH

C. 2.0 M HCl

Correct D. 2.0 M NaOH

Correct Answer: D

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Question 4

A 10.0 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 the desired temperature?

A. 1000 J

B. 10000 J

Correct C. 100000 J

D. 1000000 J

Correct Answer: C

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Question 5

A 1.0 M solution of H2SO4 is mixed with a 1.0 M solution of NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?

A. 1.0 M H2SO4

B. 1.0 M NaOH

C. 2.0 M H2SO4

Correct D. 2.0 M NaOH

Correct Answer: D

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Question 6

The rate cons\tant (k) of 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 of the reac\tant 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 7

A 2.5 g sample of a metal oxide is heated in a stream of hydrogen gas. The reaction is as follows: 2MgO(s) + 4H2(g) → 2Mg(s) + 2H2O(l). If the volume of hydrogen gas consumed is 2.5 L at 25°C and 1 atm, what is the molar mass of the metal oxide?

A. 100 g/mol

Correct B. 150 g/mol

C. 200 g/mol

D. 250 g/mol

Correct Answer: B

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Question 8

A solution containing 0.1 M glu\cose (C6H12O6) and 0.1 M fructose (C6H12O6) is prepared. If 10 mL of this solution is titrated with 0.1 M NaOH, what is the pH of the solution after the titration?

A. 7

B. 8

Correct C. 9

D. 10

Correct Answer: C

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Question 9

A 25 mL sample of a solution containing 0.1 M NaCl is mixed with 25 mL of a solution containing 0.1 M KNO3. What is the concentration of the resulting solution?

A. 0.05 M

Correct B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: B

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Question 10

A 10 mL sample of a solution containing 0.1 M HCl is mixed with 10 mL of a solution containing 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 11

A sample of an ideal gas is heated at cons\tant volume. Which of the following statements is true about the change in entropy?

A. Entropy increases

B. Entropy decreases

Correct C. Entropy remains cons\tant

D. Entropy is undefined

Correct Answer: C

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Question 12

A metal alloy is composed of 80% copper and 20% zinc. What is the empirical formula of the alloy?

A. Cu2Zn

Correct B. CuZn

C. Cu3Zn2

D. CuZn2

Correct Answer: B

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Question 13

A solution contains 2.5 g of glu\cose (C6H12O6) per 100 mL of water. What is the molarity of the solution?

A. 0.1 M

Correct B. 0.5 M

C. 1.0 M

D. 2.0 M

Correct Answer: B

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Question 14

A gas is collected over water at a temperature of 25°C and a pressure of 1 atm. What is the partial pressure of the gas?

Correct A. 0.9 atm

B. 0.95 atm

C. 1.0 atm

D. 1.05 atm

Correct Answer: A

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Question 15

A sample of a metal is heated to 800°C and then quenched in water. What is the change in entropy of the metal?

A. 10 J/K

B. 20 J/K

Correct C. 30 J/K

D. 40 J/K

Correct Answer: C

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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 combustion of 2.5 g of carbon at 298 K.

Correct A. -987.5 kJ

B. -393.5 kJ

C. 393.5 kJ

D. 987.5 kJ

Correct Answer: A

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Question 17

A 2.5 M solution of HCl is mixed with a 2.5 M solution of NaOH. Calculate the number of moles of NaCl formed.

A. 0.5 mol

Correct B. 1.0 mol

C. 1.5 mol

D. 2.0 mol

Correct Answer: B

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Question 18

A 1.0 M solution of FeSO4 is electrolyzed at 298 K. Calculate the mass of Fe deposited at the cathode after 2 hours.

A. 0.5 g

Correct B. 1.0 g

C. 1.5 g

D. 2.0 g

Correct Answer: B

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Question 19

A 1.0 M solution of H2SO4 is mixed with a 1.0 M solution of Ba(OH)2. Calculate the pH of the resulting solution.

A. 1.0

B. 2.0

Correct C. 3.0

D. 4.0

Correct Answer: C

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Question 20

A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. Calculate the number of moles of NaCl formed.

A. 0.5 mol

Correct B. 1.0 mol

C. 1.5 mol

D. 2.0 mol

Correct Answer: B

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Question 21

The rate cons\tant for the reaction 2NO(g) + O2(g) → 2NO2(g) is 0.05 s^-1 at 298 K. Calculate the rate cons\tant at 323 K, given that the activation energy is 80 kJ/mol.

A. 0.08 s^-1

Correct B. 0.10 s^-1

C. 0.12 s^-1

D. 0.15 s^-1

Correct Answer: B

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Question 22

The reaction 2H2(g) + O2(g) → 2H2O(l) has a rate cons\tant of 0.02 s^-1 at 298 K. If the activation energy is 120 kJ/mol, calculate the rate cons\tant at 323 K.

A. 0.04 s^-1

B. 0.06 s^-1

Correct C. 0.08 s^-1

D. 0.10 s^-1

Correct Answer: C

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Question 23

The reaction 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant of 0.05 s^-1 at 298 K. If the activation energy is 80 kJ/mol, calculate the rate cons\tant at 323 K.

A. 0.08 s^-1

Correct B. 0.10 s^-1

C. 0.12 s^-1

D. 0.15 s^-1

Correct Answer: B

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Question 24

The reaction 2H2(g) + O2(g) → 2H2O(l) has a rate cons\tant of 0.02 s^-1 at 298 K. If the activation energy is 120 kJ/mol, calculate the rate cons\tant at 323 K.

A. 0.04 s^-1

B. 0.06 s^-1

Correct C. 0.08 s^-1

D. 0.10 s^-1

Correct Answer: C

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Question 25

The reaction 2NO(g) + O2(g) → 2NO2(g) has a rate cons\tant of 0.05 s^-1 at 298 K. If the activation energy is 80 kJ/mol, calculate the rate cons\tant at 323 K.

A. 0.08 s^-1

Correct B. 0.10 s^-1

C. 0.12 s^-1

D. 0.15 s^-1

Correct Answer: B

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