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POST UTME ABU 2024 Chemistry | Objective

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Question 1 View Details

Calculate the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that ΔH°(Al2O3) = -1675.7 kJ/mol, ΔH°(Fe2O3) = -824.2 kJ/mol, and ΔH°(Fe) = 0 kJ/mol.

Correct A. -1352.4 kJ/mol

B. -1675.7 kJ/mol

C. -824.2 kJ/mol

D. 0 kJ/mol

Correct Answer: A

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Question 2 View Details

A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer is composed of 80% monomer A and 20% monomer B, what is the average molecular weight of monomer A?

Correct A. 80,000 g/mol

B. 100,000 g/mol

C. 120,000 g/mol

D. 140,000 g/mol

Correct Answer: A

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Question 3 View Details

A 2.5 M solution of HCl is titrated with a 1.5 M solution of NaOH. If 25 mL of NaOH is added, 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 4 View Details

A 50-g sample of a subs\tance is found to have a mass of 25 g after being heated in a furnace at 1000°C for 1 hour. What is the percentage of the subs\tance that decomposed?

A. 20%

B. 30%

Correct C. 40%

D. 50%

Correct Answer: C

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Question 5 View Details

A 2.0 M solution of H2SO4 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 2 hours, what is the mass of oxygen gas collected at the anode?

A. 0.5 g

Correct B. 1.0 g

C. 1.5 g

D. 2.0 g

Correct Answer: B

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Question 6 View Details

The rate cons\tant (k) of a first-order reaction is related to the half-life \( t_\( 1/2 \ \)) by the equation: k = ln(2) / t_\( 1/2 \). If the half-life of a reaction is 10 minutes, calculate the rate cons\tant (k) in units of min^\( -1 \).

A. 0.0693 min^\( -1 \)

Correct B. 0.693 min^\( -1 \)

C. 6.93 min^\( -1 \)

D. 69.3 min^\( -1 \)

Correct Answer: B

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Question 7 View Details

A 2.5 M solution of H_(2)SO_(4) is prepared by dissolving 2.5 g of H_(2)SO_(4) in 100 mL of water. Calculate the molarity of the solution.

A. 1.25 M

Correct B. 2.5 M

C. 5.0 M

D. 10.0 M

Correct Answer: B

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Question 8 View Details

The solubility of a subs\tance is defined as the maximum amount of the subs\tance that can dissolve in a given amount of solvent at a particular temperature. What is the unit of solubility?

A. g/L

Correct B. mol/L

C. g/mol

D. L/mol

Correct Answer: B

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Question 9 View Details

A 10 mL sample of a solution containing 0.1 M NaOH is titrated with 0.1 M HCl. Calculate the volume of HCl required to reach the equivalence point.

A. 10 mL

Correct B. 20 mL

C. 30 mL

D. 40 mL

Correct Answer: B

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Question 10 View Details

The reaction between H_(2)O and CO is catalyzed by a platinum catalyst. The rate of reaction is given by the equation: rate = k[H_(2)O][CO]. If the rate of reaction is 0.05 mol/L/min and the concentration of CO is 0.1 M, calculate the rate cons\tant (k).

A. 0.5 min^\( -1 \)

Correct B. 1.0 min^\( -1 \)

C. 2.0 min^\( -1 \)

D. 5.0 min^\( -1 \)

Correct Answer: B

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Question 11 View Details

Determine the pH of a 0.1 M solution of HCl.

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 12 View Details

A 25.0 mL sample of 0.500 M HCl is titrated with 0.100 M NaOH. Calculate the number of moles of NaOH required to reach the equivalence point.

A. 0.0125

Correct B. 0.0250

C. 0.0375

D. 0.0500

Correct Answer: B

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Question 13 View Details

A 50.0 mL sample of 0.200 M H2SO4 is titrated with 0.100 M NaOH. Calculate the pH of the solution at the equivalence point.

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 14 View Details

A 100.0 mL sample of 0.500 M HCl is titrated with 0.100 M NaOH. Calculate the volume of NaOH required to reach the equivalence point.

A. 50.0 mL

B. 75.0 mL

Correct C. 100.0 mL

D. 125.0 mL

Correct Answer: C

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Question 15 View Details

A 25.0 mL sample of 0.500 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution at the equivalence point.

Correct A. 1

B. 2

C. 3

D. 4

Correct Answer: A

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Question 16 View Details

A 0.1 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 100 mL of water. Calculate the number of moles of NaCl that will be present in 50 mL of this solution.

Correct A. 0.0125 mol

B. 0.025 mol

C. 0.05 mol

D. 0.1 mol

Correct Answer: A

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Question 17 View Details

A metal M has a density of 8.5 g/cm³ and a molar mass of 120 g/mol. If 2.5 g of M is dissolved in 100 mL of water, what is the concentration of the resulting solution in mol/L?

A. 0.02 M

Correct B. 0.04 M

C. 0.06 M

D. 0.08 M

Correct Answer: B

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Question 18 View Details

A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in 1000 mL of water. What is the concentration of the resulting solution in mol/L?

A. 0.1 M

B. 0.5 M

Correct C. 1.0 M

D. 2.0 M

Correct Answer: C

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Question 19 View Details

A metal M has a density of 7.5 g/cm³ and a molar mass of 150 g/mol. If 3.0 g of M is dissolved in 100 mL of water, what is the concentration of the resulting solution in mol/L?

A. 0.02 M

B. 0.04 M

Correct C. 0.06 M

D. 0.08 M

Correct Answer: C

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Question 20 View Details

A 0.5 M solution of NaOH is prepared by dissolving 20.0 g of NaOH in 1000 mL of water. What is the concentration of the resulting solution in mol/L?

A. 0.05 M

B. 0.1 M

Correct C. 0.5 M

D. 1.0 M

Correct Answer: C

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Question 21 View Details

A metal M reacts with chlorine gas to form a white solid product. The reaction is as follows: M + Cl2 → MX2. If 2.5 g of M is reacted with 2.5 g of Cl2, what is the limiting reac\tant?

A. M

Correct B. Cl2

C. MX2

D. Neither M nor Cl2 is the limiting reac\tant.

Correct Answer: B

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Question 22 View Details

A solution of NaOH is added to a solution of HCl. The resulting solution is a salt and water. What is the chemical equation for this reaction?

Correct A. NaOH + HCl → NaCl + H2O

B. NaOH + HCl → NaCl + H2

C. NaOH + HCl → Na2Cl + H2O

D. NaOH + HCl → NaCl + O2

Correct Answer: A

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Question 23 View Details

A 2.5 M solution of HCl is mixed with a 2.5 M solution of NaOH. What is the resulting pH of the solution?

Correct A. 7

B. 8

C. 9

D. 10

Correct Answer: A

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Question 24 View Details

A metal M reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2MO3. If 2.5 g of M is reacted with 2.5 g of O2, what is the limiting reac\tant?

A. M

Correct B. O2

C. MO3

D. Neither M nor O2 is the limiting reac\tant.

Correct Answer: B

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Question 25 View Details

A solution of HCl is added to a solution of NaOH. The resulting solution is a salt and water. What is the chemical equation for this reaction?

Correct A. HCl + NaOH → NaCl + H2O

B. HCl + NaOH → NaCl + H2

C. HCl + NaOH → Na2Cl + H2O

D. HCl + NaOH → NaCl + O2

Correct Answer: A

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