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POST UTME RSU 2019 Chemistry | Objective

Are you preparing for POST UTME RSU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2019 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), given that the initial concentrations of NO and O2 are 0.1 M and 0.2 M, respectively, and the rate of reaction is 0.05 M/s after 10 minutes.

A. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)

B. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)

Correct C. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)

D. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)

Correct Answer: C

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Question 2

A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 25.0 mL of NaOH has been added.

Correct A. \( pH = \frac{1}{2} \log \frac{[H^+] [OH^-]}{[H_2O]} \)

B. \( pH = \frac{1}{2} \log \frac{[H_2O]}{[H^+] [OH^-]} \)

C. \( pH = \frac{1}{2} \log \frac{[H^+] [OH^-]}{[H_2O]} \)

D. \( pH = \frac{1}{2} \log \frac{[H_2O]}{[H^+] [OH^-]} \)

Correct Answer: A

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Question 3

The diagram below shows the energy level diagram for a hydrogen atom. What is the energy of the electron in the 3rd orbit?

Correct A. \( E_n = -\frac{13.6}{n^2} \) eV

B. \( E_n = \frac{13.6}{n^2} \) eV

C. \( E_n = -\frac{13.6}{n} \) eV

D. \( E_n = \frac{13.6}{n} \) eV

Correct Answer: A

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Question 4

The diagram below shows the titration curve for the reaction between HCl and NaOH. What is the pH of the solution at point X?

Correct A. \( pH = \frac{1}{2} \log \frac{[H^+] [OH^-]}{[H_2O]} \)

B. \( pH = \frac{1}{2} \log \frac{[H_2O]}{[H^+] [OH^-]} \)

C. \( pH = \frac{1}{2} \log \frac{[H^+] [OH^-]}{[H_2O]} \)

D. \( pH = \frac{1}{2} \log \frac{[H_2O]}{[H^+] [OH^-]} \)

Correct Answer: A

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Question 5

The diagram below shows the structure of a molecule. What is the type of bond between atoms A and B?

Correct A. ( sigma ) bond

B. ( pi ) bond

C. ( sigma ) and ( pi ) bond

D. ( delta ) bond

Correct Answer: A

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Question 6

Determine the molar mass of the polymer formed by the condensation reaction between ethylene glycol and adipic acid. The reaction is as follows: HO-CH2-CH2-OH + HOOC-(CH2)4-COOH → HOOC-(CH2)4-CO-O-CH2-CH2-O-CO-(CH2)4-COOH + H2O

A. 180 g/mol

B. 220 g/mol

Correct C. 260 g/mol

D. 300 g/mol

Correct Answer: C

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Question 7

A 2.5 M solution of CuSO4 is electrolyzed u\sing a platinum electrode. If the current is 5.0 A and the electrolysis is carried out for 2.5 hours, what is the mass of copper deposited at the cathode?

A. 0.25 g

Correct B. 0.50 g

C. 0.75 g

D. 1.0 g

Correct Answer: B

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Question 8

A 0.1 M solution of NaCl is mixed with 0.1 M solution of AlCl3. What is the concentration of the resulting solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: B

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Question 9

A 1.0 M solution of HCl is mixed with 1.0 M solution of 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 10

A 0.1 M solution of FeCl3 is mixed with 0.1 M solution of NaOH. What is the concentration of the resulting solution?

A. 0.1 M

Correct B. 0.2 M

C. 0.3 M

D. 0.4 M

Correct Answer: B

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Question 11

The reaction of sulfur with oxygen to form sulfur dioxide is an example of a redox reaction. Write the balanced chemical equation for this reaction.

Correct A. \text{S} + \text{O}_2 \rightarrow \text{SO}_2

B. \text{S} + \text{O}_2 \rightarrow \text{SO}_3

C. \text{S} + \text{O}_2 \rightarrow \text{SO}_4

D. \text{S} + \text{O}_2 \rightarrow \text{SO}_5

Correct Answer: A

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Question 12

A solution of sodium chloride (NaCl) is prepared by dissolving 35.5 g of NaCl in 250 mL of water. What is the molarity of the solution?

A. 0.1 M

B. 0.2 M

Correct C. 0.3 M

D. 0.4 M

Correct Answer: C

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Question 13

The pH of a solution is 4.5. What is the concentration of hydrogen ions in the solution?

Correct A. 1.0 x 10^{-4.5} M

B. 1.0 x 10^{-5.5} M

C. 1.0 x 10^{-6.5} M

D. 1.0 x 10^{-7.5} M

Correct Answer: A

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Question 14

A sample of a polymer is analyzed and found to have a molecular weight of 50000 g/mol. What is the degree of polymerization of the sample?

A. 10

B. 20

Correct C. 30

D. 40

Correct Answer: C

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Question 15

A solution of sulfuric acid (H2SO4) is prepared by dissolving 25.0 g of H2SO4 in 100 mL of water. What is the concentration of the solution in terms of molarity?

A. 0.5 M

Correct B. 1.0 M

C. 1.5 M

D. 2.0 M

Correct Answer: B

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Question 16

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. -1206.58 kJ/mol

Correct Answer: A

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Question 17

A 0.500 M solution of NaOH is titrated with 0.250 M HCl. What is the pH of the solution after 25.0 mL of HCl has been added?

A. 8.00

Correct B. 8.25

C. 8.50

D. 9.00

Correct Answer: B

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Question 18

A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2MO3. If 2.50 g of M is burned in air, what is the volume of O2 consumed at STP?

A. 1.50 L

B. 1.75 L

Correct C. 2.00 L

D. 2.25 L

Correct Answer: C

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Question 19

A 0.100 M solution of FeCl3 is electrolyzed u\sing a platinum electrode. What is the mass of Cl2 gas collected at the anode after 2.00 hours?

A. 0.500 g

B. 0.750 g

Correct C. 1.00 g

D. 1.25 g

Correct Answer: C

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Question 20

A 0.500 M solution of NaOH is titrated with 0.250 M HCl. What is the pH of the solution after 25.0 mL of HCl has been added?

A. 8.00

Correct B. 8.25

C. 8.50

D. 9.00

Correct Answer: B

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Question 21

The polymerization of styrene to polystyrene is an example of a chain reaction. What type of initiator is typically used in this reaction?

Correct A. Free radical initiator

B. Cationic initiator

C. Anionic initiator

D. Ziegler-Natta catalyst

Correct Answer: A

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Question 22

A 0.500 M solution of NaCl is electrolyzed u\sing a platinum electrode. What is the mass of Cl2 gas collected at the cathode after 2.00 hours?

A. 0.250 g

B. 0.500 g

Correct C. 1.00 g

D. 2.00 g

Correct Answer: C

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Question 23

The compound SO2Cl2 is an example of a sulfuryl chloride. What is the oxidation state of the sulfur atom in this compound?

A. +2

B. +4

Correct C. +6

D. +8

Correct Answer: C

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Question 24

A 2.00 M solution of HCl 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. 1.00

Correct B. 2.00

C. 3.00

D. 4.00

Correct Answer: B

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Question 25

The compound CO2 is an example of a greenhouse gas. What is the molar mass of this compound?

Correct A. 44.01 g/mol

B. 46.01 g/mol

C. 48.01 g/mol

D. 50.01 g/mol

Correct Answer: A

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