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POST UTME DELSU 2021 Chemistry | Objective

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Question 1

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 2

A 25.0 mL sample of 0.500 M NaOH is titrated with 0.100 M HCl. What is the pH of the solution after the addition of 25.0 mL of HCl?

A. 1

B. 2

C. 3

Correct D. 4

Correct Answer: D

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Question 3

A 2.00 g sample of a polymer is dissolved in 100.0 mL of water. What is the concentration of the polymer solution in g/L?

A. 2.00

B. 4.00

Correct C. 6.00

D. 8.00

Correct Answer: C

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Question 4

A 1.00 L sample of a gas at 25.0°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. 2.00 L

D. 4.00 L

Correct Answer: C

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Question 5

A 2.00 g sample of a hydrocarbon is burned in a bomb calorimeter. The heat released is 12.0 kJ. What is the molar mass of the hydrocarbon?

A. 12.0 g/mol

B. 24.0 g/mol

Correct C. 36.0 g/mol

D. 48.0 g/mol

Correct Answer: C

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Question 6

Determine the molar mass of a polymer with the following repeating unit: CH2-CH(CH3)-CH2-CH3. Assume that the polymer has a degree of polymerization of 100.

A. 500 g/mol

Correct B. 600 g/mol

C. 700 g/mol

D. 800 g/mol

Correct Answer: B

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Question 7

A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after the addition of 25.0 mL of NaOH.

A. 2.00

Correct B. 3.00

C. 4.00

D. 5.00

Correct Answer: B

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Question 8

A 2.50 g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution is then titrated with a 0.100 M NaOH solution. Calculate the number-average molecular weight of the polymer.

A. 5000 g/mol

B. 6000 g/mol

Correct C. 7000 g/mol

D. 8000 g/mol

Correct Answer: C

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Question 9

A 1.00 M solution of a weak acid (HA) is titrated with a 1.00 M solution of a strong base (NaOH). The pH of the solution after the addition of 20.0 mL of NaOH is 4.00. Calculate the dissociation cons\tant (Ka) of the acid.

A. 1.0 x 10^\( -5 \)

Correct B. 1.0 x 10^\( -4 \)

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

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

Correct Answer: B

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Question 10

A 2.00 g sample of a polymer is dissolved in 100.0 mL of a solvent. The solution is then titrated with a 0.100 M NaOH solution. Calculate the weight-average molecular weight of the polymer.

A. 6000 g/mol

B. 7000 g/mol

Correct C. 8000 g/mol

D. 9000 g/mol

Correct Answer: C

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Question 11

A 0.500 M solution of AgNO3 is prepared by dissolving 25.0 g of AgNO3 in water to make 1000 mL of solution. Calculate the number of moles of AgNO3 used in preparing the solution.

A. 0.125 mol

B. 0.250 mol

Correct C. 0.500 mol

D. 1.00 mol

Correct Answer: C

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Question 12

The half-life of a radioactive subs\tance is 5.00 days. If 100.0 mg of the subs\tance is initially present, how much of the subs\tance will remain after 15.0 days?

A. 50.0 mg

B. 25.0 mg

C. 12.5 mg

Correct D. 6.25 mg

Correct Answer: D

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Question 13

A sample of a polymer has a molecular weight of 500,000 g/mol. If 2.50 g of the polymer is dissolved in 100.0 mL of solvent, what is the concentration of the solution in g/mL?

A. 0.0050 g/mL

B. 0.010 g/mL

C. 0.020 g/mL

Correct D. 0.050 g/mL

Correct Answer: D

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Question 14

A 2.00 M solution of HCl is prepared by dissolving 40.0 g of HCl in water to make 1000 mL of solution. Calculate the number of moles of HCl used in preparing the solution.

A. 0.200 mol

B. 0.400 mol

Correct C. 0.800 mol

D. 1.60 mol

Correct Answer: C

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Question 15

A sample of a non-metallic element has a mass of 25.0 g and a volume of 10.0 mL. What is the density of the element in g/mL?

Correct A. 2.50 g/mL

B. 2.00 g/mL

C. 1.50 g/mL

D. 1.00 g/mL

Correct Answer: A

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Question 16

Determine the number of unpaired electrons in the ground state of a neutral atom of the element with atomic number 13.

Correct A. 2

B. 4

C. 6

D. 8

Correct Answer: A

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Question 17

A 0.5 M solution of NaOH is mixed with a 0.5 M solution of HCl. What is the resulting concentration of the resulting 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

A metal M has an atomic radius of 135 pm. If the first ionization energy of M is 500 kJ/mol, what is the expected value of the second ionization energy?

A. 600 kJ/mol

Correct B. 700 kJ/mol

C. 800 kJ/mol

D. 900 kJ/mol

Correct Answer: B

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Question 19

A sample of a gas occupies a volume of 2.5 L at a pressure of 1.5 atm. If the temperature is increased to 300 K, what is the new volume of the gas?

A. 3.0 L

B. 3.5 L

Correct C. 4.0 L

D. 4.5 L

Correct Answer: C

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Question 20

A solution contains 0.1 M NaCl. What is the concentration of Cl- ions in the solution?

A. 0.05 M

Correct B. 0.1 M

C. 0.15 M

D. 0.2 M

Correct Answer: B

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Question 21

The reaction between zinc metal and copper(II) sulfate solution is represented by the equation: Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s). What is the oxidation state of copper in the product Cu(s)?

A. 0

B. +1

Correct C. +2

D. -1

Correct Answer: C

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Question 22

A 2.5 L flask contains 0.25 mol of an ideal gas at 298 K. What is the pressure of the gas in the flask?

Correct A. 1.01 × 10^5 Pa

B. 2.02 × 10^5 Pa

C. 3.03 × 10^5 Pa

D. 4.04 × 10^5 Pa

Correct Answer: A

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Question 23

The half-life of a radioactive subs\tance is 5.0 years. If 100 g of the subs\tance initially contains 50 g of the radioactive isotope, how much of the isotope will remain after 10 years?

Correct A. 12.5 g

B. 25 g

C. 37.5 g

D. 50 g

Correct Answer: A

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Question 24

A solution of sodium chloride (NaCl) is prepared by dissolving 35.5 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 25

A 2.0 M solution of hydrochloric acid (HCl) is prepared by dissolving 40 g of HCl in 250 mL of water. What is the concentration of HCl in the solution?

A. 1.6 M

Correct B. 2.0 M

C. 2.4 M

D. 2.8 M

Correct Answer: B

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