POST UTME UNIBEN 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 25 mL sample of 0.1 M NaOH is titrated with 0.1 M HCl. Calculate the pH of the solution after 10 mL of HCl has been added.
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 2
A 1.0 M solution of HCl is mixed with a 1.0 M solution of NaOH. If the resulting solution is 1.0 M in NaCl, what is the concentration of the hydrogen ion \( H+ \) in the solution?
A. 1.0 × 10^\( -7 \) M
B. 1.0 × 10^\( -6 \) M
C. 1.0 × 10^\( -5 \) M
D. 1.0 × 10^\( -4 \) M
Question 3
The electronegativity of an element is a measure of its ability to attract electrons in a covalent bond. Which of the following elements has the highest electronegativity among the given options?
A. Fluorine (F)
B. Chlorine (Cl)
C. Bromine (Br)
D. Iodine (I)
Question 4
A 2.5 g sample of a metal is heated in a Bunsen burner flame. If the temperature of the metal increases by 50°C, what is the specific heat capacity of the metal?
A. 0.1 J/g°C
B. 0.5 J/g°C
C. 1 J/g°C
D. 5 J/g°C
Question 5
A solution of 10 g of NaOH in 100 g of water has a pH of 14. What is the concentration of the solution?
A. 0.1 M
B. 0.5 M
C. 1 M
D. 5 M
Question 6
A 2.5 L flask contains 0.5 M H2SO4. What is the concentration of H+ ions in the solution?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 7
A polymer is composed of 80% polyethylene and 20% polypropylene. If the density of polyethylene is 0.95 g/cm^3 and the density of polypropylene is 0.9 g/cm^3, calculate the average density of the polymer.
A. 0.92 g/cm^3
B. 0.95 g/cm^3
C. 0.98 g/cm^3
D. 1.0 g/cm^3
Question 8
A 2.0 g sample of a polymer is dissolved in 100 mL of a solvent. If the polymer has a molecular weight of 50,000 g/mol, what is the concentration of the polymer in the solution?
A. 0.1 g/mL
B. 0.2 g/mL
C. 0.3 g/mL
D. 0.4 g/mL
Question 9
A solution containing 0.1 M AgNO3 is electrolyzed u\sing a platinum electrode. If the current is 0.5 A and the time is 2 hours, calculate the mass of silver deposited.
A. 0.05 g
B. 0.1 g
C. 0.15 g
D. 0.2 g
Question 10
The s\tandard enthalpy of formation of CO$\( _2$ \) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of H$\( _2$ \)O($l$) if the s\tandard enthalpy of formation of H$\( _2$ \) is -285.8 kJ/mol and the s\tandard enthalpy of formation of O$\( _2$ \) is 0 kJ/mol.
A. -241.8 kJ/mol
B. -285.8 kJ/mol
C. -393.5 kJ/mol
D. -285.8 kJ/mol + 393.5 kJ/mol
Question 11
A 0.1 M solution of NaOH is mixed with a 0.1 M solution of HCl. If the resulting solution is 0.1 M in NaCl, what is the concentration of the hydroxide ion \( OH- \) in the solution?
A. 1.0 × 10^\( -7 \) M
B. 1.0 × 10^\( -6 \) M
C. 1.0 × 10^\( -5 \) M
D. 1.0 × 10^\( -4 \) M
Question 12
A polymer has a molecular weight of 50000 g/mol and a degree of polymerization of 100. Calculate the molar mass of the repeating unit.
A. 500 g/mol
B. 5000 g/mol
C. 50000 g/mol
D. 500000 g/mol
Question 13
A 10% solution of NaCl is prepared by dissolving 10 g of NaCl in 90 g of water. Calculate the molarity of the solution.
A. 0.1 M
B. 0.5 M
C. 1 M
D. 5 M
Question 14
A 0.1 M solution of NaOH is mixed with a 0.1 M solution of HCl. If the resulting solution is 0.1 M in NaCl, what is the concentration of the hydroxide ion \( OH- \) in the solution?
A. 1.0 × 10^\( -7 \) M
B. 1.0 × 10^\( -6 \) M
C. 1.0 × 10^\( -5 \) M
D. 1.0 × 10^\( -4 \) M
Question 15
Determine the pH of a solution containing 0.1 M HCl and 0.2 M NaOH.
A. 7
B. 8
C. 9
D. 10

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