POST UTME UNIBEN 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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 2
A polymer is a large molecule composed of many repeated subunits called monomers. Which of the following types of polymers is known for its high tensile strength and is often used in the production of textiles?
A. Polyethylene
B. Polypropylene
C. Polyester
D. Polyvinyl Chloride
Question 3
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 4
A solution contains 0.05 M H2SO4. Calculate the pH of the solution.
A. 1
B. 2
C. 3
D. 4
Question 5
A metal has a density of 8 g/cm3 and a volume of 2 cm3. What is the mass of the metal?
A. 16 g
B. 18 g
C. 20 g
D. 22 g
Question 6
A solution of 10 g of NaCl in 100 g of water has a boiling point elevation of 0.5°C. What is the molar mass of NaCl?
A. 58.5 g/mol
B. 59.5 g/mol
C. 60.5 g/mol
D. 61.5 g/mol
Question 7
The half-life of a radioactive subs\tance is 5 years. If the initial activity is 1000 Bq, calculate the activity after 10 years.
A. 500 Bq
B. 750 Bq
C. 1000 Bq
D. 1250 Bq
Question 8
Calculate the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that ΔH°(Al2O3) = -1675 kJ/mol, ΔH°(Fe2O3) = -824 kJ/mol, and ΔH°(Fe) = 0 kJ/mol.
A. -2869 kJ/mol
B. -1675 kJ/mol
C. -824 kJ/mol
D. 2869 kJ/mol
Question 9
A solution of 10 g of glu\cose in 100 g of water has a freezing point depression of 0.2°C. What is the molar mass of glu\cose?
A. 180 g/mol
B. 200 g/mol
C. 220 g/mol
D. 240 g/mol
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
The half-life of a radioactive subs\tance is 5 years. If a sample initially contains 100 g of the subs\tance, how much of the subs\tance will remain after 20 years?
A. 12.5 g
B. 25 g
C. 50 g
D. 100 g
Question 12
The reaction between sodium (Na) and chlorine (Cl2) produces sodium chloride (NaCl). If 2.5 g of Na is reacted with 3.2 g of Cl2, what is the limiting reac\tant?
A. Na
B. Cl2
C. NaCl
D. Neither
Question 13
A sample of a gas has a volume of 2.5 L at a pressure of 1 atm and a temperature of 298 K. Calculate the number of moles of the gas.
A. 0.1 mol
B. 0.2 mol
C. 0.3 mol
D. 0.4 mol
Question 14
The rate cons\tant (k) for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, calculate the concentration after 10 minutes.
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 15
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

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