POST UTME CHRISTOPHER UNIVERSITY 2017 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The half-life of a radioactive subs\tance is 5 years. Calculate the activity of 1 gram of the subs\tance after 10 years.
A. 0.1
B. 0.5
C. 1
D. 2
Question 2
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of CH4(g) from the following reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l).
A. -74.8 kJ/mol
B. -74.9 kJ/mol
C. -75.0 kJ/mol
D. -75.1 kJ/mol
Question 3
Determine the molar solubility of AgCl in a 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) of AgCl is 1.8 × 10^\( -10 \) and the solubility product cons\tant (Ksp) of NaCl is 3.2 × 10^\( -9 \).
A. 1.0 × 10^\( -5 \) M
B. 1.5 × 10^\( -5 \) M
C. 2.0 × 10^\( -5 \) M
D. 2.5 × 10^\( -5 \) M
Question 4
A 0.1 M solution of NaOH is mixed with a 0.1 M solution of HCl. What is the pH of the resulting solution?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 5
A metal (M) reacts with chlorine gas to form a white solid. The reaction is represented by the equation: 2M + Cl2 → 2MCl. If 2.5 g of M is reacted with 1.5 g of Cl2, what is the limiting reac\tant?
A. M
B. Cl2
C. Neither
D. Both
Question 6
A sample of a hydrocarbon with the molecular formula C5H12 is found to have a density of 0.65 g/mL. What is the molar mass of the hydrocarbon?
A. 70 g/mol
B. 80 g/mol
C. 90 g/mol
D. 100 g/mol
Question 7
A hydrocarbon has the molecular formula C4H10. What is the type of hydrocarbon?
A. Alkane
B. Alkene
C. Alkyne
D. Aromatic hydrocarbon
Question 8
A 2.5 M solution of NaCl is prepared by dissolving 12.5 g of NaCl in 4.0 L of water. What is the concentration of Na+ ions in the solution?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 9
A redox reaction involves the oxidation of Fe2+ to Fe3+ and the reduction of MnO4- to Mn2+. What is the oxidation number of Mn in MnO4-?
A. +7
B. +6
C. +5
D. +4
Question 10
The s\tandard enthalpy of formation \( ΔH_f^∘ \) for CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation for C(s) + O2(g) → CO2(g)?
A. -393.5 kJ/mol
B. -393.5 kJ/mol + 0 kJ/mol
C. -393.5 kJ/mol - 0 kJ/mol
D. -393.5 kJ/mol + 0 kJ/mol + 0 kJ/mol
Question 11
Determine the pH of a solution containing 0.1 M HCl and 0.1 M NaOH.
A. 1
B. 2
C. 3
D. 4
Question 12
A diagram of a titration setup is shown below. If 25.0 mL of 1.00 M NaOH is added to 50.0 mL of 2.50 M HCl, what is the pH of the solution?
A. 2.00
B. 3.00
C. 4.00
D. 5.00
Question 13
A solution containing 0.1 M HCl and 0.1 M NaOH is titrated with 0.1 M H2SO4. Calculate the pH of the solution after 20 mL of H2SO4 has been added.
A. 1
B. 2
C. 3
D. 4
Question 14
A 25 mL sample of 0.5 M H2SO4 is titrated with 0.5 M NaOH. Calculate the number of moles of H2SO4.
A. 0.05
B. 0.1
C. 0.15
D. 0.2
Question 15
Calculate the molar mass of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.
A. 12.0 g/mol
B. 24.0 g/mol
C. 36.0 g/mol
D. 48.0 g/mol

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