POST UTME ACHIEVERS UNIVERSITY 2021 Chemistry | Objective

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Question 1
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 20 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 2
Determine the s\tandard enthalpy change for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that the s\tandard enthalpy of formation for Al2O3(s) is -1675.7 kJ/mol and the s\tandard enthalpy of formation for Fe(s) is 0 kJ/mol.
A. -3331.4 kJ/mol
B. -1667.85 kJ/mol
C. -1675.7 kJ/mol
D. -1000 kJ/mol
Question 3
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the volume of HCl in liters?
A. 0.25 L
B. 0.50 L
C. 0.75 L
D. 1.00 L
Question 4
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. Calculate the pH of the resulting solution after the reaction is complete.
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 5
A 1.00 M solution of CH3OH is prepared by dissolving 18.0 g of CH3OH in 100.0 mL of water. Calculate the mole \fraction of CH3OH in the solution.
A. 0.100
B. 0.200
C. 0.300
D. 0.400
Question 6
The reaction between H2S and O2 is given by the equation: 2H2S + 3O2 → 2H2O + 2SO3. Calculate the volume of O2 required to react with 2.50 L of H2S at STP.
A. 1.50 L
B. 2.25 L
C. 3.00 L
D. 4.50 L
Question 7
A 0.100 M solution of HCl is titrated with a 0.100 M solution of NaOH. If 50.0 mL of NaOH is required to reach the equivalence point, what is the volume of HCl required to reach the equivalence point?
A. 25.0 mL
B. 50.0 mL
C. 75.0 mL
D. 100 mL
Question 8
A 0.500 M solution of HCl is titrated with a 0.500 M solution of NaOH. If 25.0 mL of NaOH is required to reach the equivalence point, what is the volume of HCl required to reach the equivalence point?
A. 25.0 mL
B. 50.0 mL
C. 75.0 mL
D. 100 mL
Question 9
A diagram of a metal oxide is shown below. If the molar mass of the metal oxide is 200 g/mol, what is the molar mass of the metal?
A. 100
B. 150
C. 200
D. 250
Question 10
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1.00 mol of C(s) at 298 K.
A. -393.5 kJ/mol
B. -393.0 kJ/mol
C. -392.5 kJ/mol
D. -392.0 kJ/mol
Question 11
The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of vaporization of 1.00 mol of H2O(l) at 298 K.
A. -40.7 kJ/mol
B. -41.2 kJ/mol
C. -41.7 kJ/mol
D. -42.2 kJ/mol
Question 12
A 25.0 cm3 sample of a solution containing 0.100 M NaOH is mixed with 25.0 cm3 of 0.100 M HCl. Calculate the concentration of Na+ ions in the resulting solution.
A. 0.005 M
B. 0.010 M
C. 0.015 M
D. 0.020 M
Question 13
Determine the molar mass of a polymer with the following monomer units: CH2=CH-CH3, CH2=CH-CH2-CH3, and CH2=CH-CH2-CH2-CH3. The molar mass of the repeating unit is 56.11 g/mol. What is the molar mass of the polymer with a degree of polymerization of 500?
A. 28055.0 g/mol
B. 28105.0 g/mol
C. 28255.0 g/mol
D. 28305.0 g/mol
Question 14
A 10.0 cm3 sample of a solution containing 0.100 M K2Cr2O7 is mixed with 20.0 cm3 of 0.100 M H2SO4. Calculate the concentration of Cr3+ ions in the resulting solution.
A. 0.0025 M
B. 0.0050 M
C. 0.0075 M
D. 0.010 M
Question 15
A polymer is formed by the condensation reaction between a diol and a diacid. If 2.5 g of the diol and 3.2 g of the diacid are used, and the molecular weight of the diol is 62 g/mol and that of the diacid is 74 g/mol, calculate the number of moles of the polymer formed.
A. 0.04 mol
B. 0.06 mol
C. 0.08 mol
D. 0.10 mol

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