POST UTME DELSU 2019 Chemistry | Objective

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Question 1
A solution of sodium chloride is prepared by dissolving 35.5 g of sodium chloride in 100 mL of water. What is the molarity of the solution?
A. 0.5 M
B. 1.0 M
C. 2.0 M
D. 3.0 M
Question 2
A gas at 25°C and 1 atm is compressed to 2 atm. If the volume of the gas is reduced by a factor of 2, what is the new temperature of the gas?
A. 50°C
B. 75°C
C. 100°C
D. 125°C
Question 3
The reaction between chlorine gas and sodium hydroxide solution is represented by the equation: Cl2 + 2NaOH → NaCl + NaClO + H2O. What is the oxidation state of chlorine in the product NaClO?
A. 0
B. +1
C. +3
D. +5
Question 4
A diagram of a titration setup is shown below. What is the purpose of the burette in this setup?
A. To measure the volume of the titrant
B. To measure the volume of the analyte
C. To mix the titrant and analyte
D. To measure the pH of the solution
Question 5
A 10 mL sample of a 0.05 M solution of Fe2+ is mixed with 10 mL of a 0.05 M solution of MnO4-. If the initial concentration of Fe2+ is 0.05 M, what is the concentration of Fe3+ after the reaction is complete?
A. 0.02 M
B. 0.03 M
C. 0.04 M
D. 0.05 M
Question 6
A 0.1 M solution of a weak acid HA is mixed with a 0.1 M solution of a weak base B. If the resulting solution has a pH of 5.5, what is the value of the acid dissociation cons\tant Ka?
A. \( 10^{-5} \)
B. \( 10^{-6} \)
C. \( 10^{-7} \)
D. \( 10^{-8} \)
Question 7
A 100 mL sample of a solution containing 0.1 M HCl is mixed with 50 mL of a solution containing 0.2 M NaOH. Calculate the pH of the resulting solution.
A. 1
B. 2
C. 3
D. 4
Question 8
A diagram of a chromatography setup is shown below. What is the purpose of the stationary phase in this setup?
A. To separate the components of a mixture
B. To identify the components of a mixture
C. To measure the concentration of a component
D. To measure the pH of a solution
Question 9
Calculate the pH of a solution containing 0.1 M HCl and 0.1 M NaOH. The dissociation cons\tant of HCl is 10^-7.
A. 1
B. 2
C. 3
D. 4
Question 10
A 25 mL sample of a 0.1 M solution of NaOH is titrated with a 0.1 M solution of HCl. If the initial pH of the NaOH solution is 12.5, what is the pH of the resulting solution after the reaction is complete?
A. 1.5
B. 2.5
C. 3.5
D. 4.5
Question 11
A sample of a polymer is analyzed by infrared spectroscopy. What is the expected frequency of the C-H stretching vibration?
A. 2800 cm^-1
B. 3000 cm^-1
C. 3200 cm^-1
D. 3400 cm^-1
Question 12
Determine the number of moles of sulfur trioxide (SO3) produced when 2.50 g of sulfur (S) is heated in the presence of oxygen (O2) according to the equation: 2S + 3O2 → 2SO3. The molar mass of sulfur is 32.07 g/mol, and the molar mass of sulfur trioxide is 80.07 g/mol.
A. 0.0625 mol
B. 0.125 mol
C. 0.25 mol
D. 0.5 mol
Question 13
A 2.5 M solution of sodium hydroxide (NaOH) is prepared by dissolving 25.0 g of NaOH in 1.0 L of water. Calculate the concentration of the solution in units of molarity (M) if 25.0 g of NaOH is dissolved in 1.0 L of water.
A. 1.0 M
B. 2.0 M
C. 2.5 M
D. 5.0 M
Question 14
What is the molar mass of a compound with the empirical formula C2H4O?
A. 28 g/mol
B. 40 g/mol
C. 56 g/mol
D. 72 g/mol
Question 15
The half-life of a radioactive subs\tance is 5.0 days. If 100.0 mg of the subs\tance is initially present, how much of the subs\tance will remain after 20.0 days?
A. 25.0 mg
B. 50.0 mg
C. 75.0 mg
D. 100.0 mg

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