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POST UTME REDEEMERS UNIVERSITY 2023 Chemistry | Objective

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Question 1

Determine the empirical formula of a compound containing 40.0 g of carbon, 6.0 g of hydrogen, and 54.0 g of oxygen.

Correct A. CH2O

B. C2H4O2

C. C3H6O3

D. C4H8O4

Correct Answer: A

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Question 2

A 2.5 L flask contains 0.50 mol of an ideal gas at 25°C. What is the pressure of the gas?

A. 1.0 atm

Correct B. 2.0 atm

C. 3.0 atm

D. 4.0 atm

Correct Answer: B

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Question 3

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 the titration?

A. 7.0

Correct B. 8.0

C. 9.0

D. 10.0

Correct Answer: B

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Question 4

A 50.0 g sample of a polymer is dissolved in 100.0 mL of solvent. What is the concentration of the solution?

A. 0.50 g/mL

Correct B. 1.0 g/mL

C. 2.0 g/mL

D. 3.0 g/mL

Correct Answer: B

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Question 5

A 100.0 mL sample of a 0.10 M solution of glu\cose is titrated with 0.10 M HCl. What is the pH of the solution after the titration?

A. 6.0

Correct B. 7.0

C. 8.0

D. 9.0

Correct Answer: B

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Question 6

The rate cons\tant (k) for a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 120 kJ/mol, the gas cons\tant (R) is 8.314 J/\( mol*K \), and the temperature (T) is 300 K, what is the value of the rate cons\tant (k) if the pre-exponential factor (A) is 1.0 x 10^10 s^\( -1 \)?

Correct A. 1.0 x 10^\( -5 \) s^\( -1 \)

B. 1.0 x 10^\( -4 \) s^\( -1 \)

C. 1.0 x 10^\( -3 \) s^\( -1 \)

D. 1.0 x 10^\( -2 \) s^\( -1 \)

Correct Answer: A

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Question 7

A 0.100 M solution of NaOH is titrated with 0.100 M HCl. If 25.0 mL of HCl is required to reach the equivalence point, what is the number of moles of NaOH present in the original solution?

A. 0.00250 mol

Correct B. 0.00500 mol

C. 0.00750 mol

D. 0.0100 mol

Correct Answer: B

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Question 8

The reaction of hydrogen gas with chlorine gas to form hydrogen chloride is an example of a reaction that involves the formation of a new bond between two atoms. What is the type of bond that is formed between the hydrogen and chlorine atoms in this reaction?

A. ionic

Correct B. covalent

C. metallic

D. hydrogen bond

Correct Answer: B

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Question 9

The diagram below shows a titration setup for the reaction of sodium hydroxide with hydrochloric acid. What is the purpose of the burette in this setup?

Correct A. to measure the volume of acid added

B. to measure the volume of base added

C. to mix the acid and base

D. to separate the acid and base

Correct Answer: A

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Question 10

The reaction of sodium hydroxide with hydrochloric acid is an example of a reaction that involves the formation of a new compound. What is the name of the compound that is formed in this reaction?

Correct A. sodium chloride

B. sodium hydroxide

C. hydrochloric acid

D. water

Correct Answer: A

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Question 11

The atomic radius of an element is 100 pm. If the element is in the 4th period and has an atomic number of 18, what is the expected value of its atomic radius in the next period?

A. 120 pm

B. 140 pm

Correct C. 160 pm

D. 180 pm

Correct Answer: C

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Question 12

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

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 13

A sample of water contains 10 ppm of Cl- ions. What is the concentration of Cl- ions in mg/L?

A. 0.1 mg/L

B. 1 mg/L

Correct C. 10 mg/L

D. 100 mg/L

Correct Answer: C

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Question 14

A 2.0 g sample of a polymer is dissolved in 100 mL of solvent. What is the concentration of the polymer in g/L?

A. 20 g/L

Correct B. 40 g/L

C. 60 g/L

D. 80 g/L

Correct Answer: B

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Question 15

A 0.1 M solution of H2SO4 is titrated with 0.1 M NaOH. What is the pH of the solution after 50 mL of NaOH has been added?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 16

The reaction of cyclohexane with bromine in the presence of light produces 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-1,2-dibromocyclohexane

Correct Answer: B

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Question 17

A 2.50-g sample of a compound containing only carbon and hydrogen is burned in a combustion calorimeter. The volume of carbon dioxide produced is 2.00 L at 25°C and 1.00 atm. What is the empirical formula of the compound?

A. CH

Correct B. C2H2

C. C3H4

D. C4H6

Correct Answer: B

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Question 18

A solution of 0.100 M NaCl is prepared by dissolving 10.0 g of NaCl in 1.00 L of water. What is the concentration of Cl- ions in the solution?

A. 0.0500 M

Correct B. 0.100 M

C. 0.200 M

D. 0.500 M

Correct Answer: B

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Question 19

A 25.0-mL sample of a solution containing 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the solution after the titration is complete?

A. 7.00

Correct B. 8.00

C. 9.00

D. 10.0

Correct Answer: B

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Question 20

A diagram of a titration apparatus is shown below. What is the purpose of the burette in this apparatus?

Correct A. To measure the volume of the titrant

B. To measure the volume of the analyte

C. To mix the titrant and analyte

D. To separate the titrant and analyte

Correct Answer: A

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Question 21

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 22

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

Correct A. 1.01 × 10^5 Pa

B. 2.01 × 10^5 Pa

C. 3.01 × 10^5 Pa

D. 4.01 × 10^5 Pa

Correct Answer: A

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Question 23

A solution contains 0.100 M KNO3. What is the concentration of K+ ions?

Correct A. 0.0500 M

B. 0.100 M

C. 0.150 M

D. 0.200 M

Correct Answer: A

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Question 24

A 5.00 g sample of a metal is heated in a Bunsen burner flame. The mass of the metal remaining after heating is 3.50 g. What is the percentage of the metal that is lost during heating?

A. 30.0%

B. 40.0%

Correct C. 50.0%

D. 60.0%

Correct Answer: C

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Question 25

A 2.00 M solution of NaOH is mixed with a 1.00 M solution of HCl. What is the resulting concentration of Na+ ions?

A. 0.500 M

Correct B. 1.00 M

C. 1.50 M

D. 2.00 M

Correct Answer: B

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