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POST UTME REDEEMERS UNIVERSITY 2017 Chemistry | Objective

Are you preparing for POST UTME REDEEMERS 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

Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g) at 298 K, given that the initial concentrations of NO and O2 are 0.1 M and 0.05 M, respectively, and the rate of reaction is 3.2 × 10^\( -3 \) M/s.

Correct A. \( 3.2 \times 10^{-3} \) M/s

B. \( 1.6 \times 10^{-3} \) M/s

C. \( 6.4 \times 10^{-3} \) M/s

D. \( 1.28 \times 10^{-3} \) M/s

Correct Answer: A

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Question 2

A 0.5 M solution of NaOH is titrated with 0.1 M HCl. Calculate the pH of the solution after 25 mL of HCl has been added.

A. ( 2.5 )

Correct B. ( 3.5 )

C. ( 4.5 )

D. ( 5.5 )

Correct Answer: B

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Question 3

A metal (X) reacts with dilute HCl to produce a gas that gives a brown precipitate with KI solution. Identify the metal (X) and the gas produced.

A. Cu, SO2

Correct B. Zn, SO2

C. Fe, SO2

D. Pb, SO2

Correct Answer: B

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Question 4

A 2.5 g sample of a metal (X) is heated in a stream of oxygen to produce a green-colored solid. The mass of the solid produced is 3.2 g. Calculate the percentage yield of the reaction.

A. ( 80% )

B. ( 85% )

Correct C. ( 90% )

D. ( 95% )

Correct Answer: C

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Question 5

A solution containing 0.1 M CuSO4 is mixed with a solution containing 0.1 M NaOH. Calculate the concentration of Cu(OH)2 formed after the reaction is complete.

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 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. -1206.60 kJ/mol

B. -1206.61 kJ/mol

C. -1206.59 kJ/mol

D. -1206.62 kJ/mol

Correct Answer: A

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Question 7

A 2.50 L flask contains 0.500 mol of an ideal gas at 25°C. Calculate the pressure of the gas.

A. 1.01 x 10^5 Pa

Correct B. 2.01 x 10^5 Pa

C. 3.01 x 10^5 Pa

D. 4.01 x 10^5 Pa

Correct Answer: B

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Question 8

The half-life of a radioactive subs\tance is 5.00 years. If 100.0 g of the subs\tance initially decays to 50.0 g, how many years will it take for the subs\tance to decay to 12.5 g?

A. 10.00 years

B. 15.00 years

Correct C. 20.00 years

D. 25.00 years

Correct Answer: C

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Question 9

A 1.00 M solution of HCl is titrated with 0.500 M NaOH. Calculate the pH of the solution after 25.0 mL of NaOH has been added.

A. 2.00

Correct B. 3.00

C. 4.00

D. 5.00

Correct Answer: B

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Question 10

A 2.00 g sample of a polymer is dissolved in 100.0 mL of solvent. The solution has a vis\cosity of 1.50 cP. Calculate the molar mass of the polymer.

A. 100.0 g/mol

B. 200.0 g/mol

Correct C. 300.0 g/mol

D. 400.0 g/mol

Correct Answer: C

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Question 11

The reaction of cyclohexane with bromine in the presence of light yields a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?

A. 1,2-dibromocyclohexane

Correct B. 1,4-dibromocyclohexane

C. cis-1,2-dibromocyclohexane

D. trans-1,4-dibromocyclohexane

Correct Answer: B

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Question 12

A 2.50 g sample of an unknown hydrocarbon is burned in a bomb calorimeter. The heat of combustion is - 37.5 kJ/g. What is the molar mass of the hydrocarbon?

A. 50 g/mol

B. 100 g/mol

Correct C. 150 g/mol

D. 200 g/mol

Correct Answer: C

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Question 13

The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol and the s\tandard enthalpy of formation of O2(g) is 0 kJ/mol?

Correct A. -285.8 kJ/mol

B. -241.8 kJ/mol

C. -393.5 kJ/mol

D. -483.5 kJ/mol

Correct Answer: A

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Question 14

A 0.500 M solution of HCl is titrated with a 0.500 M solution of NaOH. What is the pH of the solution after the addition of 25.0 mL of NaOH?

A. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 15

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 the addition of 50.0 mL of NaOH?

A. 1.00

B. 2.00

Correct C. 3.00

D. 4.00

Correct Answer: C

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Question 16

The atomic radius of an element in the periodic table increases down a group due to the addition of new energy levels. However, the atomic radius of an element in the periodic table decreases across a period due to the increase in effective nuclear charge. What is the correct explanation for this tr\end?

A. The addition of new energy levels increases the atomic radius.

Correct B. The increase in effective nuclear charge decreases the atomic radius.

C. The atomic radius is inversely proportional to the atomic number.

D. The atomic radius is directly proportional to the atomic number.

Correct Answer: B

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Question 17

A 2.5 M solution of HCl is prepared by dissolving 25 g of HCl in 1 L of water. What is the pH of the solution?

Correct A. 1.3

B. 2.5

C. 3.5

D. 4.5

Correct Answer: A

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Question 18

A 50 mL sample of a solution containing 0.1 M NaOH is titrated with 0.1 M HCl. What is the pH of the solution after the addition of 25 mL of HCl?

A. 1.3

B. 2.5

Correct C. 3.5

D. 4.5

Correct Answer: C

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Question 19

A 1 L solution of 0.1 M NaOH is prepared by dissolving 10 g of NaOH in 1 L of water. What is the concentration of OH- ions in the solution?

A. 0.01 M

Correct B. 0.1 M

C. 1 M

D. 10 M

Correct Answer: B

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Question 20

A 2.5 M solution of HCl is prepared by dissolving 25 g of HCl in 1 L of water. What is the concentration of H+ ions in the solution?

A. 0.01 M

Correct B. 0.1 M

C. 1 M

D. 10 M

Correct Answer: B

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