POST UTME BOWEN UNIVERSITY 2020 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The rate cons\tant of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?
A. 0.05 M
B. 0.025 M
C. 0.1 M
D. 0.5 M
Question 2
A solution of sodium chloride is prepared by dissolving 35.5 g of NaCl in 250 mL of water. Calculate the molarity of the solution.
A. 0.15 M
B. 0.20 M
C. 0.25 M
D. 0.30 M
Question 3
The compound SO2 is a non-metal oxide. What is the oxidation state of sulfur in SO2?
A. +2
B. -2
C. +4
D. -4
Question 4
A 2.0 L flask contains 0.20 M NaOH solution. If 5.0 mL of 1.0 M HCl is added to the solution, calculate the new concentration of the solution.
A. 0.22 M
B. 0.25 M
C. 0.28 M
D. 0.30 M
Question 5
The atomic radius of an element is 100 pm. If the element is in the 4th period, what is the expected value of its atomic radius in the next period?
A. 120 pm
B. 140 pm
C. 160 pm
D. 180 pm
Question 6
Determine the pH of a 0.1 M solution of HCl after 10 mL of 1 M NaOH has been added to 20 mL of the HCl solution. Assume the volume of the solution remains cons\tant.
A. 1
B. 2
C. 3
D. 4
Question 7
A 2.5 M solution of NaOH is mixed with a 1.5 M solution of HCl. If 50 mL of the NaOH solution is added to 100 mL of the HCl solution, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 8
The rate cons\tant (k) for a first-order reaction is related to the half-life \( t_\( 1/2 \ \)) by the equation: k = ln(2) / t_\( 1/2 \). If the half-life of a reaction is 10 minutes, calculate the rate cons\tant (k) in min^\( -1 \).
A. 0.0693 min^\( -1 \)
B. 0.693 min^\( -1 \)
C. 6.93 min^\( -1 \)
D. 69.3 min^\( -1 \)
Question 9
The compound NH3 is a non-metal hydride. What is the oxidation state of nitrogen in NH3?
A. -3
B. +3
C. +5
D. -5
Question 10
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. If 2.5 mol of CO2 is formed at 298 K, what is the total enthalpy change for the reaction?
A. -987.5 kJ
B. -993.5 kJ
C. -998.5 kJ
D. -1002.5 kJ
Question 11
A polymer is formed by the condensation reaction between a diol and a diacid. If the molecular weight of the diol is 180 g/mol and the molecular weight of the diacid is 150 g/mol, what is the molecular weight of the polymer formed?
A. 450
B. 600
C. 900
D. 1200
Question 12
A mixture of 25.0 g of ethanol (C2H5OH) and 15.0 g of propanol (C3H7OH) is heated to produce a gas. If the total volume of the gas produced is 2.5 L at 25°C and 1 atm, calculate the percentage of ethanol in the mixture.
A. 60%
B. 65%
C. 70%
D. 75%
Question 13
A 1 M solution of a weak acid, HA, is titrated with 1 M NaOH. The initial pH of the acid is 3. The equivalence point is reached when 20 mL of NaOH is added. What is the pH of the solution at the equivalence point?
A. 7
B. 9
C. 11
D. 13
Question 14
The reaction between sodium hydroxide and hydrochloric acid is a neutralization reaction. Write the balanced equation for the reaction.
A. NaOH + HCl → NaCl + H2O
B. NaOH + HCl → NaCl + H2O2
C. NaOH + HCl → NaCl + H2
D. NaOH + HCl → NaCl + CO2
Question 15
A solution of 10 g of NaCl in 100 g of water has a boiling point elevation of 0.5°C. What is the molality of the solution?
A. 0.1 m
B. 0.2 m
C. 0.3 m
D. 0.4 m

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