POST UTME CRAWFORD UNIVERSITY 2025 Chemistry | Objective

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Question 1 View Details
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO(g)?
Correct A. -110.5 kJ/mol
B. -393.5 kJ/mol
C. 110.5 kJ/mol
D. 393.5 kJ/mol

Correct Answer: A

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Question 2 View Details
A 0.5 M solution of NaOH is mixed with a 0.5 M solution of HCl. What is the pH of the resulting solution?
Correct A. 7
B. 8
C. 9
D. 10

Correct Answer: A

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Question 3 View Details
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 after 10 minutes?
Correct A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M

Correct Answer: A

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Question 4 View Details
A metal M reacts with oxygen to form a basic oxide MO. The reaction is as follows: 4M + 3O2 → 2MO2. What is the oxidation number of M?
A. +2
Correct B. +3
C. +4
D. +5

Correct Answer: B

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Question 5 View Details
The diagram below shows a titration setup. What is the purpose of the burette?
Correct A. To measure the volume of the solution
B. To measure the concentration of the solution
C. To mix the solutions
D. To heat the solution

Correct Answer: A

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Question 6 View Details
A sample of a metal oxide has a mass of 25.0 g and a volume of 5.00 cm³. If the density of the metal oxide is 6.00 g/cm³, what is the number of moles of oxygen present in the sample?
A. 0.500 mol
Correct B. 1.00 mol
C. 1.50 mol
D. 2.00 mol

Correct Answer: B

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Question 7 View Details
A solution of HCl is prepared by dissolving 35.5 g of HCl in 250 mL of water. What is the molarity of the solution?
A. 0.150 M
B. 0.250 M
Correct C. 0.350 M
D. 0.450 M

Correct Answer: C

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Question 8 View Details
A gas at 25°C and 1 atm expands from 2.00 L to 4.00 L. What is the work done by the gas?
A. 100 J
Correct B. 200 J
C. 300 J
D. 400 J

Correct Answer: B

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Question 9 View Details
A sample of a metal has a mass of 50.0 g and a volume of 10.0 cm³. If the density of the metal is 8.00 g/cm³, what is the number of moles of metal present in the sample?
A. 0.625 mol
B. 1.25 mol
Correct C. 1.88 mol
D. 2.50 mol

Correct Answer: C

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Question 10 View Details
A solution of NaOH is prepared by dissolving 25.0 g of NaOH in 500 mL of water. What is the molarity of the solution?
A. 0.100 M
B. 0.200 M
Correct C. 0.300 M
D. 0.400 M

Correct Answer: C

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Question 11 View Details
A polymer is formed by the condensation reaction between two monomers. If the molecular weight of the monomer is 180 g/mol and the molecular weight of the polymer is 3600 g/mol, what is the degree of polymerization?
A. 10
Correct B. 20
C. 30
D. 40

Correct Answer: B

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Question 12 View Details
A solution of sulfuric acid (H2SO4) is 0.5 M. What is the concentration of hydrogen ions \( H+ \) in the solution?
Correct A. 0.25 M
B. 0.5 M
C. 1 M
D. 2 M

Correct Answer: A

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Question 13 View Details
A sample of nitrogen gas (N2) has a volume of 2.5 L at a pressure of 1 atm and a temperature of 273 K. What is the number of moles of nitrogen gas?
A. 0.01 mol
Correct B. 0.1 mol
C. 1 mol
D. 10 mol

Correct Answer: B

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Question 14 View Details
A solution of sodium chloride (NaCl) is 0.2 M. What is the concentration of chloride ions \( Cl- \) in the 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 15 View Details
A sample of oxygen gas (O2) has a volume of 1.5 L at a pressure of 2 atm and a temperature of 300 K. What is the number of moles of oxygen gas?
A. 0.05 mol
B. 0.1 mol
Correct C. 0.5 mol
D. 1 mol

Correct Answer: C

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Question 16 View Details
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the equivalence point is reached at 35.0 mL of NaOH, what is the pH of the resulting solution?
A. 1.00
B. 2.00
Correct C. 3.00
D. 4.00

Correct Answer: C

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Question 17 View Details
A solution contains 0.500 mol of KCl and 0.250 mol of NaCl. What is the total number of moles of chloride ions in the solution?
A. 0.500
B. 0.750
Correct C. 1.000
D. 1.250

Correct Answer: C

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Question 18 View Details
A 2.00 L flask contains 0.100 mol of CO2 at 25°C. What is the partial pressure of CO2 in the flask?
A. 0.100
B. 0.200
Correct C. 0.300
D. 0.400

Correct Answer: C

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Question 19 View Details
A 0.500 M solution of HCl is titrated with 0.500 M NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the pH of the resulting solution?
A. 1.00
B. 2.00
Correct C. 3.00
D. 4.00

Correct Answer: C

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Question 20 View Details
A 1.00 L flask contains 0.0500 mol of O2 at 25°C. What is the partial pressure of O2 in the flask?
A. 0.0500
B. 0.100
Correct C. 0.150
D. 0.200

Correct Answer: C

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Question 21 View Details
A solution of 0.50 M NaCl is prepared by dissolving 0.50 g of NaCl in 100 mL of water. What is the concentration of the solution in g/L?
A. 0.50 g/L
B. 0.25 g/L
Correct C. 1.00 g/L
D. 2.00 g/L

Correct Answer: C

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Question 22 View Details
A polymer has a molecular weight of 100,000 g/mol. If 1.00 g of the polymer is dissolved in 100 mL of water, what is the concentration of the solution in g/L?
A. 0.10 g/L
Correct B. 1.00 g/L
C. 10.0 g/L
D. 100 g/L

Correct Answer: B

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Question 23 View Details
A gas mixture contains 20% O2, 30% N2, and 50% CO2 by volume. What is the partial pressure of CO2 in a sample of the gas at 1.00 atm total pressure?
A. 0.50 atm
B. 0.75 atm
Correct C. 1.00 atm
D. 1.25 atm

Correct Answer: C

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Question 24 View Details
A solution of 0.10 M HCl is prepared by dissolving 0.10 g of HCl in 100 mL of water. What is the concentration of the solution in g/L?
Correct A. 0.10 g/L
B. 0.25 g/L
C. 0.50 g/L
D. 1.00 g/L

Correct Answer: A

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Question 25 View Details
A polymer has a molecular weight of 50,000 g/mol. If 0.50 g of the polymer is dissolved in 100 mL of water, what is the concentration of the solution in g/L?
A. 0.05 g/L
B. 0.10 g/L
C. 0.25 g/L
Correct D. 0.50 g/L

Correct Answer: D

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