POST UTME KSU 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A metal is extracted from its ore through a process involving the reduction of the metal oxide with carbon. The reaction is represented by the equation:
A. The metal is iron.
B. The metal is copper.
C. The metal is zinc.
D. The metal is lead.
Question 2
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 3
Determine the pH of a 0.1 M solution of HCl in water at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \).
A. 1
B. 2
C. 3
D. 4
Question 4
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 5
A polymer is formed by the condensation reaction between a diol and a diisocyanate. The reaction is represented by the equation:
A. The polymer is a thermoplastic.
B. The polymer is a thermoset.
C. The polymer is a elastomer.
D. The polymer is a ceramic.
Question 6
A 2.5 g sample of a polymer is dissolved in 100 mL of a solvent. If the density of the solution is 1.2 g/mL, what is the molar mass of the polymer?
A. 1000 g/mol
B. 2000 g/mol
C. 5000 g/mol
D. 10000 g/mol
Question 7
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. \( % yield = \frac{mass of MCl_2 produced}{mass of M used} \times 100% \)
Question 8
A solution contains 0.5 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the new concentration of NaCl?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.5 M
Question 9
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of H2O(l) if the s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol and the s\tandard enthalpy of formation of H2(g) is 0 kJ/mol?
A. -285.8 kJ/mol
B. -241.8 kJ/mol
C. -393.5 kJ/mol
D. -572.8 kJ/mol
Question 10
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 11
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. \( % yield = \frac{mass of MCl_2 produced}{mass of M used} \times 100% \)
Question 12
A polymer is made up of repeating units of the following structure: CH2=CH-COOH. What is the name of this polymer?
A. Polyethylene
B. Polypropylene
C. Polyvinyl alcohol
D. Polyacrylic acid
Question 13
A 2.50 L flask contains 0.500 mol of CO2(g) at 25°C. What is the pressure of the gas in the flask?
A. 3.00 atm
B. 4.00 atm
C. 5.00 atm
D. 6.00 atm
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 0.1 M solution of HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is added, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4

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