POST UTME KSU 2020 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen gas (H2) react with oxygen gas according to the equation: 2H2 + O2 → 2H2O.
A. 1.25 mol
B. 2.5 mol
C. 5.0 mol
D. 7.5 mol
Question 2
The diagram below shows a titration setup. What is the purpose of the burette?
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 3
The energy change associated with the formation of a mole of a solid from its gaseous reac\tants is typically
A. exothermic
B. \endothermic
C. neither exothermic nor \endothermic
D. dep\endent on the specific reaction
Question 4
A 2.0 M solution of HCl is titrated with 1.0 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?
A. 7
B. 8
C. 9
D. 10
Question 5
A certain metal (M) reacts with chlorine gas (Cl2) to form a metal chloride (MCl2). If 2.0 g of the metal chloride is obtained from 3.2 g of the metal, calculate the percentage yield of the metal chloride.
A. 60%
B. 70%
C. 80%
D. 90%
Question 6
A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl2 → MCl2. If 2.50 g of MCl2 is formed from 1.50 g of M, what is the molar mass of M?
A. 50.0 g/mol
B. 75.0 g/mol
C. 100 g/mol
D. 150 g/mol
Question 7
A sample of a polymer has a molecular weight of 50000 g/mol. If the polymer has a degree of polymerization of 200, what is the molecular weight of the repeating unit?
A. 250 g/mol
B. 250 g/mol
C. 250 g/mol
D. 250 g/mol
Question 8
The atomic radius of an element decreases across a period in the periodic table. Which of the following is a correct explanation for this tr\end?
A. The effective nuclear charge increases across a period.
B. The atomic radius increases across a period.
C. The number of electrons in the outermost energy level increases across a period.
D. The atomic radius remains cons\tant across a period.
Question 9
A 2.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. The vapor pressure of water at 25°C is 23.8 mmHg. Calculate the partial pressure of the gas.
A. 0.97 atm
B. 0.98 atm
C. 0.99 atm
D. 1.00 atm
Question 10
A sample of a gas at 25°C and 1 atm is heated to 50°C at cons\tant volume. What is the new pressure of the gas, assuming ideal gas behavior?
A. 1.5 atm
B. 2 atm
C. 3 atm
D. 4 atm
Question 11
A diagram of a simple titration apparatus is shown below. If 25.0 mL of a 0.5 M solution of sodium hydroxide (NaOH) is added to 25.0 mL of a 0.2 M solution of hydrochloric acid (HCl), calculate the pH of the resulting solution.
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 12
A 2.5 M solution of NaOH is titrated with 0.5 M HCl. What is the pH of the solution after 25 mL of HCl has been added?
A. 9
B. 10
C. 11
D. 12
Question 13
The diagram below shows a titration setup. What is the purpose of the burette?
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 separate the titrant and analyte.
Question 14
A 1.00 M solution of HCl is titrated with 1.00 M NaOH. What is the pH of the solution after 10.0 mL of NaOH has been added?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 15
A 2.00 M solution of H2SO4 is titrated with 1.00 M NaOH. What is the pH of the solution after 20.0 mL of NaOH has been added?
A. 1.00
B. 2.00
C. 3.00
D. 4.00

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