POST UTME DELSU 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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?
A. 12.5 g
B. 25 g
C. 37.5 g
D. 50 g
Question 2
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^\( -5 \)
B. 1.0 x 10^\( -4 \)
C. 1.0 x 10^\( -3 \)
D. 1.0 x 10^\( -2 \)
Question 3
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
C. +2
D. -1
Question 4
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
B. 3.00
C. 4.00
D. 5.00
Question 5
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
C. 0.500 mol
D. 1.00 mol
Question 6
Determine the number of unpaired electrons in the ground state of a neutral atom of the element with atomic number 13.
A. 2
B. 4
C. 6
D. 8
Question 7
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
D. 0.050 g/mL
Question 8
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
C. 8000 g/mol
D. 9000 g/mol
Question 9
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
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 10
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
C. 2.00 L
D. 4.00 L
Question 11
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?
A. 2.50 g/mL
B. 2.00 g/mL
C. 1.50 g/mL
D. 1.00 g/mL
Question 12
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
B. 2.0 M
C. 2.4 M
D. 2.8 M
Question 13
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
C. 4.0 L
D. 4.5 L
Question 14
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
C. 7000 g/mol
D. 8000 g/mol
Question 15
A solution contains 0.1 M NaCl. What is the concentration of Cl- ions in the solution?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M

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