POST UTME ABU 2018 Chemistry | Objective

Are you preparing for POST UTME ABU exams? Reviewing past questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2018 Chemistry (Objective) questions designed to simulate the real exam environment.

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Question 1
A polymer is formed by the condensation reaction between two monomers, A and B. The molecular weight of the polymer is 500 g/mol. If the molecular weights of monomers A and B are 150 g/mol and 200 g/mol, respectively, what is the average molecular weight of the monomers that reacted to form the polymer?
A. 100 g/mol
Correct B. 150 g/mol
C. 200 g/mol
D. 250 g/mol

Correct Answer: B

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Question 2
A solution contains 2.5 g of NaCl in 250 mL of water. What is the molarity of 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 3
A first-order reaction has a rate cons\tant of 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration after 10 minutes?
A. 0.05 M
B. 0.1 M
Correct C. 0.15 M
D. 0.2 M

Correct Answer: C

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Question 4
A solution contains 10 g of glu\cose in 100 mL of water. What is the concentration of the solution in g/L?
Correct A. 100 g/L
B. 200 g/L
C. 300 g/L
D. 400 g/L

Correct Answer: A

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Question 5
A cell contains 0.1 M glu\cose and 0.1 M oxygen. If the cell is 100 mL in volume, what is the concentration of glu\cose and oxygen in the cell?
Correct A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M

Correct Answer: A

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Question 6
The reaction of sodium with chlorine gas is highly exothermic. If 2.5 g of sodium reacts with 1.5 g of chlorine gas, what is the limiting reac\tant?
Correct A. Sodium
B. Chlorine
C. Neither
D. Both

Correct Answer: A

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Question 7
A solution contains 0.1 M NaOH and 0.2 M HCl. 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 8
The diagram below shows a titration setup. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, 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 9
A solution contains 0.1 M NaOH and 0.2 M HCl. 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 10
The diagram below shows a titration setup. If 25 mL of 0.1 M NaOH is added to 25 mL of 0.1 M HCl, 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
A polymer is formed by the condensation reaction between a diol and a diacid. The molecular weight of the polymer is 50,000 g/mol. If the molecular weight of the diol is 180 g/mol and that of the diacid is 120 g/mol, what is the average molecular weight of the repeating unit of the polymer?
A. 150
B. 180
Correct C. 200
D. 220

Correct Answer: C

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Question 12
A solution of HCl is titrated with a solution of NaOH. The initial pH of the solution is 2. If 25 mL of 1 M NaOH is added to 50 mL of 0.5 M HCl, what is the pH of the solution after the addition of the NaOH?
A. 3
Correct B. 4
C. 5
D. 6

Correct Answer: B

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Question 13
A metal M has an atomic radius of 200 pm and a valency of 2. If the ionic radius of M2+ is 150 pm, what is the percentage increase in the atomic radius of M when it forms the M2+ ion?
A. 25
Correct B. 30
C. 35
D. 40

Correct Answer: B

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Question 14
A solution of NaCl is electrolyzed u\sing a current of 5 A for 2 hours. If the molar mass of NaCl is 58.5 g/mol, what is the mass of NaCl deposited at the cathode?
A. 0.5
B. 1
Correct C. 1.5
D. 2

Correct Answer: C

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Question 15
A mixture of 2 g of NaCl and 3 g of KCl is dissolved in 100 mL of water. If the density of the solution is 1.2 g/mL, what is the molality of the solution?
A. 0.1
B. 0.2
Correct C. 0.3
D. 0.4

Correct Answer: C

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Question 16
A 2.50 L sample of a gas at 27°C is collected over water at 23°C. If the total pressure is 755 mmHg, what is the partial pressure of the gas?
Correct A. 740 mmHg
B. 755 mmHg
C. 770 mmHg
D. 785 mmHg

Correct Answer: A

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Question 17
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. What is the pH of the solution after the addition of 25.0 mL of NaOH?
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 18
A 10.0 g sample of a polymer is dissolved in 100.0 mL of solvent. What is the molar mass of the polymer if the osmotic pressure is 2.50 atm at 25°C?
A. 1000 g/mol
Correct B. 2000 g/mol
C. 3000 g/mol
D. 4000 g/mol

Correct Answer: B

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Question 19
A 50.0 mL sample of a solution containing 0.100 M NaCl is mixed with 50.0 mL of a solution containing 0.100 M KNO3. What is the concentration of Cl- ions in the resulting solution?
A. 0.0500 M
B. 0.0750 M
Correct C. 0.100 M
D. 0.125 M

Correct Answer: C

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Question 20
A 100.0 mL sample of a solution containing 0.100 M H2SO4 is titrated with 0.100 M NaOH. What is the pH of the solution after the addition of 50.0 mL of NaOH?
A. 1.00
B. 2.00
C. 3.00
Correct D. 4.00

Correct Answer: D

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Question 21
The rate cons\tant 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. 0.005 M
B. 0.05 M
C. 0.1 M
D. 1 M

Correct Answer: A

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Question 22
A sample of gas occupies 2.5 L at 27°C and 1 atm. What is the volume of the gas at 37°C and 2 atm?
Correct A. 1.25 L
B. 2.5 L
C. 5 L
D. 10 L

Correct Answer: A

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Question 23
A 2.0 g sample of a subs\tance is dissolved in 100 mL of water. If the molarity of the solution is 0.5 M, what is the molar mass of the subs\tance?
A. 10 g/mol
Correct B. 20 g/mol
C. 40 g/mol
D. 80 g/mol

Correct Answer: B

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Question 24
A 100 mL sample of a solution containing 0.5 M HCl is mixed with 100 mL of a solution containing 0.5 M NaOH. What is the concentration of the resulting solution?
A. 0.5 M
B. 1 M
Correct C. 1.5 M
D. 2 M

Correct Answer: C

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Question 25
A 2.0 g sample of a subs\tance is burned in a bomb calorimeter. If the heat released is 12 kJ, what is the molar heat of combustion of the subs\tance?
A. -6000 J/mol
Correct B. -12000 J/mol
C. -24000 J/mol
D. -48000 J/mol

Correct Answer: B

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