POST UTME KSU 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.0 g sample of a metal oxide is treated with 20 mL of 1 M HCl. The reaction is carried out in a 100 mL beaker. Calculate the number of moles of CO2 produced, given that the molar mass of the metal oxide is 160 g/mol and the molar mass of CO2 is 44 g/mol.
A. 0.05
B. 0.1
C. 0.15
D. 0.2
Question 2
The s\tandard enthalpy of formation (ΔH°f) for CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion (ΔH°c) for 1 mol of C(s) at 298 K.
A. -393.5 kJ/mol
B. -393.5 kJ/mol + 298 kJ/mol
C. -393.5 kJ/mol - 298 kJ/mol
D. -393.5 kJ/mol + 298 kJ/mol + 298 kJ/mol
Question 3
A 2.5 L flask contains 0.5 mol of an ideal gas at a temperature of 300 K. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.5 atm
B. 2.5 atm
C. 3.0 atm
D. 4.0 atm
Question 4
The reaction of cyclohexane with bromine in the presence of light produces a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?
A. 1,2-dibromocyclohexane
B. 1,4-dibromocyclohexane
C. cis-1,2-dibromocyclohexane
D. trans-1,4-dibromocyclohexane
Question 5
A solution of sodium chloride is added to a solution of silver nitrate. What is the precipitate formed?
A. AgCl
B. NaNO3
C. NaCl
D. AgNO3
Question 6
A base is a subs\tance that is a strong electrolyte and has a pH greater than 7. Which of the following is a base?
A. Sodium hydroxide (NaOH)
B. Sodium chloride (NaCl)
C. Sodium carbonate (Na2CO3)
D. Sodium sulfate (Na2SO4)
Question 7
A 2.0 g sample of a non-metallic element is heated in a crucible until it melts. If the mass of the crucible and the melted element is 2.5 g, what is the molar mass of the element?
A. 50 g/mol
B. 100 g/mol
C. 200 g/mol
D. 500 g/mol
Question 8
A 0.1 M solution of NaOH is titrated with 0.1 M HCl. The pH of the solution at the equivalence point is 7. Calculate the pH of the solution at the half-equivalence point.
A. \( pH = \frac{1}{2} \times pH_{eq} \)
B. \( pH = \frac{1}{2} \times pH_{initial} \)
C. \( pH = pH_{eq} - \frac{1}{2} \times pH_{initial} \)
D. \( pH = pH_{eq} + \frac{1}{2} \times pH_{initial} \)
Question 9
The half-life of a radioactive subs\tance is 5.3 years. If the initial amount of the subs\tance is 100 g, how much of the subs\tance will remain after 21.4 years?
A. 10 g
B. 20 g
C. 30 g
D. 40 g
Question 10
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
Question 11
A 1.0 M solution of NaOH is mixed with a 1.0 M solution of HCl. What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 12
A 2.5 g sample of a metal carbonate is treated with 20 mL of 1 M HCl. The reaction is carried out in a 100 mL beaker. Calculate the number of moles of CO2 produced, given that the molar mass of the metal carbonate is 120 g/mol and the molar mass of CO2 is 44 g/mol.
A. 0.05
B. 0.1
C. 0.15
D. 0.2
Question 13
The reaction of cyclohexane with bromine in the presence of light yields a mixture of 1,2-dibromocyclohexane and 1,4-dibromocyclohexane. What is the major product of this reaction?
A. 1,2-dibromocyclohexane
B. 1,4-dibromocyclohexane
C. cis-1,2-dibromocyclohexane
D. trans-1,4-dibromocyclohexane
Question 14
The reaction between nitrogen dioxide and water produces nitric acid and nitric oxide. Write the balanced chemical equation for this reaction.
A. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{NO}
B. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{O}_2 + \text{NO}
C. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_3 + \text{H}_2\text{O}
D. \text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{O}_2 + \text{HNO}_3
Question 15
A metal (M) reacts with chlorine gas to form a white solid. The reaction is as follows: M + Cl2 → MCl2. If 2.5 g of M reacts with 1.5 g of Cl2, what is the percentage yield of MCl2?
A. \( % yield = \frac{mass of MCl_2 produced}{theoretical mass of MCl_2} \times 100% \)
B. \( % yield = \frac{mass of M used}{theoretical mass of MCl_2} \times 100% \)
C. \( % yield = \frac{mass of Cl_2 used}{theoretical mass of MCl_2} \times 100% \)
D. \( % yield = \frac{mass of MCl_2 produced}{mass of M used} \times 100% \)

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