POST UTME REDEEMERS UNIVERSITY 2021 Chemistry | Objective

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Question 1 View Details
A 2.50-g sample of a hydrocarbon is burned in excess oxygen to produce 3.75 L of CO2 at 25°C and 1.00 atm. What is the empirical formula of the hydrocarbon?
Correct A. C2H4
B. C3H6
C. C4H8
D. C5H10

Correct Answer: A

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Question 2 View Details
The rate cons\tant for the decomposition of N2O5 is 2.50 × 10^\( -3 \) s^\( -1 \) at 25°C. What is the half-life of the reaction?
Correct A. 1.38 × 10^3 s
B. 2.76 × 10^3 s
C. 4.14 × 10^3 s
D. 5.52 × 10^3 s

Correct Answer: A

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Question 3 View Details
A solution contains 0.100 M NH3 and 0.100 M HCl. What is the concentration of NH4Cl in the solution?
A. 0.100 M
Correct B. 0.200 M
C. 0.300 M
D. 0.400 M

Correct Answer: B

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Question 4 View Details
A 25.0-mL sample of a solution containing 0.200 M KI is mixed with 25.0 mL of 0.200 M AgNO3. What is the concentration of AgI in the solution?
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 5 View Details
A 2.50-g sample of a hydrocarbon is burned in excess oxygen to produce 3.75 L of CO2 at 25°C and 1.00 atm. What is the empirical formula of the hydrocarbon?
Correct A. C2H4
B. C3H6
C. C4H8
D. C5H10

Correct Answer: A

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Question 6 View Details
Determine the molar solubility of AgCl in 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) for AgCl is 1.8 × 10^\( -10 \).
Correct A. 1.0 × 10^\( -5 \) M
B. 1.0 × 10^\( -6 \) M
C. 1.0 × 10^\( -7 \) M
D. 1.0 × 10^\( -8 \) M

Correct Answer: A

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Question 7 View Details
A 25.0 mL sample of 0.100 M HCl is added to 50.0 mL of 0.0500 M NaOH. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.100 M
Correct C. 0.150 M
D. 0.200 M

Correct Answer: C

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Question 8 View Details
A metal (X) has a s\tandard electrode potential of +0.80 V. What is the s\tandard electrode potential of the metal (Y) that is reduced at the same rate as X?
A. +0.60 V
Correct B. +0.80 V
C. +1.00 V
D. +1.20 V

Correct Answer: B

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Question 9 View Details
A 2.00 g sample of a polymer is dissolved in 100.0 mL of water. What is the concentration of the solution in g/L?
A. 2.00 g/L
Correct B. 4.00 g/L
C. 6.00 g/L
D. 8.00 g/L

Correct Answer: B

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Question 10 View Details
A 1.00 L sample of a gas at 25°C and 1.00 atm is compressed to 2.00 atm at cons\tant temperature. What is the new volume of the gas?
A. 0.500 L
B. 1.00 L
Correct C. 1.50 L
D. 2.00 L

Correct Answer: C

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Question 11 View Details
Determine the number of moles of oxygen gas (O2) required to completely combust 2.5 moles of propane (C3H8) according to the balanced equation: C3H8 + 5O2 → 3CO2 + 4H2O.
A. 0.5 mol
Correct B. 1.25 mol
C. 2.5 mol
D. 5 mol

Correct Answer: B

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Question 12 View Details
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
B. 3
Correct C. 4
D. 5

Correct Answer: C

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Question 13 View Details
The diagram below shows a titration setup. Identify the part labeled A.
Correct A. Burette
B. Beaker
C. Conical Flask
D. Cylinder

Correct Answer: A

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Question 14 View Details
A sample of a polymer has a molecular weight of 100,000 g/mol. Calculate the number of monomer units in the polymer.
A. 100
B. 1000
Correct C. 10,000
D. 100,000

Correct Answer: C

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Question 15 View Details
The diagram below shows a periodic table. Identify the element with atomic number 6.
Correct A. Carbon
B. Oxygen
C. Nitrogen
D. Fluorine

Correct Answer: A

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Question 16 View Details
A 2.5 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 2.0 g, calculate the percentage yield of the metal oxide.
A. 40%
B. 50%
Correct C. 60%
D. 70%

Correct Answer: C

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Question 17 View Details
A solution of sodium hydroxide (NaOH) is titrated with a solution of hydrochloric acid (HCl). If 25.0 mL of NaOH solution is required to neutralize 20.0 mL of HCl solution, calculate the concentration of the NaOH solution.
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 18 View Details
A colloidal solution of starch in water is treated with a few drops of iodine solution. Describe the change observed.
Correct A. The solution becomes blue.
B. The solution becomes colorless.
C. The solution becomes cloudy.
D. The solution becomes clear.

Correct Answer: A

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Question 19 View Details
A sample of a metal hydroxide is dissolved in water to produce a solution with a pH of 10.5. Calculate the concentration of the metal hydroxide solution.
A. 0.01 M
B. 0.05 M
Correct C. 0.1 M
D. 0.5 M

Correct Answer: C

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Question 20 View Details
A solution of sodium chloride (NaCl) is electrolyzed u\sing a current of 5.0 A for 2.0 hours. Calculate the mass of chlorine gas produced at the anode.
A. 10 g
B. 20 g
Correct C. 30 g
D. 40 g

Correct Answer: C

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Question 21 View Details
Determine the number of moles of electrons transferred in the electrolysis of 1.5 L of 0.25 M H2SO4.
A. 1.5 mol
Correct B. 0.375 mol
C. 0.75 mol
D. 3 mol

Correct Answer: B

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Question 22 View Details
A 2.5 g sample of a non-metallic oxide is heated in a crucible until it decomposes completely. If 1.2 g of the oxide is left after heating, what is the percentage of the oxide that decomposed?
A. 20%
B. 30%
Correct C. 40%
D. 50%

Correct Answer: C

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Question 23 View Details
A metal M has a density of 9.5 g/cm3 and an atomic mass of 65.5 g/mol. What is the volume of 1.5 mol of M in cm3?
A. 0.15 cm3
B. 0.30 cm3
Correct C. 0.45 cm3
D. 0.60 cm3

Correct Answer: C

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Question 24 View Details
A solution of HCl is 0.25 M. What is the pH of the solution?
A. 0.5
Correct B. 1
C. 1.5
D. 2

Correct Answer: B

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Question 25 View Details
A metal M has a density of 9.5 g/cm3 and an atomic mass of 65.5 g/mol. What is the volume of 1.5 mol of M in cm3?
A. 0.15 cm3
B. 0.30 cm3
Correct C. 0.45 cm3
D. 0.60 cm3

Correct Answer: C

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