POST UTME BOWEN UNIVERSITY 2020 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The half-life of a radioactive subs\tance is 5 years. If 100 g of the subs\tance is initially present, what is the mass of the subs\tance remaining after 10 years?
A. 25 g
B. 50 g
C. 75 g
D. 100 g
Question 2
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, what is the volume of HCl required to reach the equivalence point?
A. 10 mL
B. 20 mL
C. 30 mL
D. 40 mL
Question 3
A sample of soil contains 10% clay, 20% silt, and 70% sand. If 100 g of this soil is taken, what is the mass of clay present in the sample?
A. 10 g
B. 20 g
C. 30 g
D. 40 g
Question 4
The reaction between nitrogen dioxide and oxygen is given by the equation: 2NO2(g) + O2(g) → 2NO3(g). At 25°C, the equilibrium cons\tant (Kp) for this reaction is 1.5 × 10^\( -2 \). If the partial pressure of NO2 is 0.5 atm, what is the partial pressure of O2 at equilibrium?
A. 0.1 atm
B. 0.2 atm
C. 0.5 atm
D. 1.0 atm
Question 5
A 5.0 L flask contains 0.50 M NaCl solution. If 10.0 mL of 2.0 M HCl is added to the solution, calculate the new concentration of the solution.
A. 0.55 M
B. 0.60 M
C. 0.65 M
D. 0.70 M
Question 6
A sample of a hydrocarbon \( C_\( 5 \ \)H_(12)) has a mass of 50.0 g. If the molar mass of the hydrocarbon is 72 g/mol, calculate the number of moles of the hydrocarbon present.
A. 0.694 mol
B. 0.6945 mol
C. 0.6947 mol
D. 0.695 mol
Question 7
The reaction between chlorine gas and potassium iodide is a redox reaction. Write the balanced half-equations for the reaction.
A. Cl2 + 2KI → 2KCl + I2
B. 2KI + Cl2 → 2KCl + I2
C. KI + Cl2 → KCl + I2
D. 2KI + Cl2 → 2KCl + 2I2
Question 8
A solution contains 2 M HCl and 1 M NaOH. If 10 mL of the solution is titrated with 1 M NaOH, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 9
A 2.5 M solution of sulfuric acid \( H_\( 2 \ \)SO_(4)) is mixed with a 1.0 M solution of sodium hydroxide (NaOH). If the reaction is complete, what is the concentration of the resulting solution?
A. 1.5 M
B. 2.0 M
C. 2.5 M
D. 3.0 M
Question 10
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 11
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 12
A sample of air contains 20% oxygen, 70% nitrogen, and 10% carbon dioxide by volume. What is the partial pressure of oxygen in a sample of air at 1 atm total pressure?
A. 0.2 atm
B. 0.4 atm
C. 0.6 atm
D. 0.8 atm
Question 13
A 2.5 g sample of a hydrocarbon is burned in a combustion calorimeter. If the volume of carbon dioxide gas produced is 2.2 L at 25°C and 1 atm, calculate the molar mass of the hydrocarbon.
A. 120 g/mol
B. 150 g/mol
C. 180 g/mol
D. 200 g/mol
Question 14
The atomic number of an element is 12. If the element has 3 electrons in its outermost shell, what is the expected oxidation state of the element in a compound?
A. 2
B. 3
C. 4
D. 5
Question 15
A 10% solution of sulfuric acid (H2SO4) is mixed with a 10% solution of sodium hydroxide (NaOH). What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4

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