POST UTME AAUA 2018 Chemistry | Objective

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Question 1
A 10.0 mL sample of a solution containing 0.25 M NaCl is diluted to a total volume of 50.0 mL. What is the concentration of the resulting solution?
A. 0.005 M
B. 0.01 M
C. 0.05 M
D. 0.1 M
Question 2
A solution contains 0.0500 M HCl and 0.0500 M NaOH. What is the concentration of the resulting solution after the reaction is complete?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 3
A 5.0 g sample of a hydrocarbon \( C_xH_y \) is burned in a combustion tube, producing 10.0 mL of CO2 and 15.0 mL of H2O. What is the empirical formula of the hydrocarbon?
A. C2H6
B. C3H8
C. C4H10
D. C5H12
Question 4
A 2.0 M solution of HCl is titrated with 1.0 M NaOH. If 20 mL of NaOH is required to reach the equivalence point, calculate the initial concentration of HCl.
A. 1.0 M
B. 1.5 M
C. 2.0 M
D. 2.5 M
Question 5
A solution contains 0.1 M HCl and 0.1 M NaOH. What is the pH of the solution?
A. 1
B. 2
C. 3
D. 4
Question 6
A sample of oxygen gas occupies a volume of 2.50 L at a pressure of 1.00 atm and a temperature of 298 K. What is the number of moles of oxygen gas present in the sample?
A. 1.00 mol
B. 2.00 mol
C. 3.00 mol
D. 4.00 mol
Question 7
A 1.0 M solution of NaOH is titrated with 2.0 M HCl. If 20 mL of HCl is required to reach the equivalence point, calculate the initial concentration of NaOH.
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 8
The reaction of hydrogen gas with oxygen gas is represented by the equation: 2H2(g) + O2(g) → 2H2O(l). What is the balanced equation for the reaction of hydrogen gas with oxygen gas in the presence of a catalyst?
A. 2H2(g) + O2(g) → 2H2O(l)
B. H2(g) + O2(g) → H2O(l)
C. 2H2(g) + O2(g) → 4H2O(l)
D. H2(g) + O2(g) → 2H2O(l)
Question 9
A 0.500 g sample of a metal carbonate is heated to produce a 0.250 g sample of the metal oxide. What is the percentage yield of the metal oxide if the theoretical yield is 0.300 g?
A. 75%
B. 80%
C. 85%
D. 90%
Question 10
The s\tandard enthalpy of formation (ΔHf°) for CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation for C(s) u\sing the following reaction: C(s) + O2(g) → CO2(g).
A. -393.5 kJ/mol
B. +393.5 kJ/mol
C. -393.0 kJ/mol
D. +393.0 kJ/mol
Question 11
The s\tandard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation of CO(g) from the following reaction: CO(g) + H2O(l) → CO2(g) + H2(g).
A. -110.5 kJ/mol
B. -110.6 kJ/mol
C. -110.7 kJ/mol
D. -110.8 kJ/mol
Question 12
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen gas (H2) react with excess oxygen gas according to the equation: 2H2 + O2 → 2H2O.
A. 1.25 moles
B. 2.5 moles
C. 5.0 moles
D. 6.25 moles
Question 13
A 2.00 g sample of an unknown hydrocarbon is burned in a combustion calorimeter. The heat of combustion is -3930 kJ/mol. Calculate the molar mass of the hydrocarbon.
A. 50.0 g/mol
B. 60.0 g/mol
C. 70.0 g/mol
D. 80.0 g/mol
Question 14
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 15
A 2.50 g sample of a metal hydroxide is dissolved in water to produce a solution with a pH of 10.50. What is the concentration of the metal ion in the solution?
A. 0.100 M
B. 0.150 M
C. 0.200 M
D. 0.250 M

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