POST UTME NOUN 2020 Chemistry | Objective

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Question 1
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation of CO(g)?
A. -110.5 kJ/mol
B. -110.5 kJ/mol
C. -110.5 kJ/mol
D. -110.5 kJ/mol
Question 2
A solution containing 0.1 M NaCl is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 10 minutes, what is the volume of hydrogen gas produced at STP?
A. 0.5 L
B. 1 L
C. 2 L
D. 5 L
Question 3
A 2.0 L flask contains 0.5 mol of an ideal gas at 27°C. Calculate the pressure of the gas in atm.
A. 1.0 atm
B. 2.0 atm
C. 3.0 atm
D. 4.0 atm
Question 4
A solution contains 5.0 g of NaCl in 250 mL of water. What is the molarity of the solution?
A. 0.2 M
B. 0.5 M
C. 1.0 M
D. 2.0 M
Question 5
A solution of sodium hydroxide (NaOH) has a pH of 12. If the concentration of NaOH is 0.1 M, calculate the concentration of hydrogen ions (H⁺) in the solution.
A. 1.0 × 10⁻¹² M
B. 1.0 × 10⁻¹¹ M
C. 1.0 × 10⁻¹⁰ M
D. 1.0 × 10⁻⁹ M
Question 6
A 2.0 M solution of HCl is mixed with a 2.0 M solution of NaOH. If the initial concentrations of HCl and NaOH are 2.0 M each, what is the concentration of NaCl that will be formed after the reaction is complete?
A. 2.0 M
B. 1.0 M
C. 0.5 M
D. 0.25 M
Question 7
A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer has a density of 1.2 g/cm³, calculate the molar mass of the polymer in g/mol.
A. 83,333 g/mol
B. 83,333.33 g/mol
C. 83,333.34 g/mol
D. 83,333.35 g/mol
Question 8
The reaction of sodium with water is represented by the equation: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g). Calculate the number of moles of hydrogen gas produced when 2.5 g of sodium reacts with excess water.
A. 0.25 mol
B. 0.50 mol
C. 0.75 mol
D. 1.00 mol
Question 9
A 2.50 g sample of a compound containing only C, H, and O is analyzed by combustion. The volume of CO2 produced is 2.50 L at 25°C and 1.00 atm. The volume of H2O produced is 1.00 L at 25°C and 1.00 atm. Calculate the empirical formula of the compound.
A. C2H4O
B. C3H6O
C. C4H8O
D. C5H10O
Question 10
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy change for the reaction: CO(g) + 1/2O2(g) → CO2(g).
A. -196.75 kJ/mol
B. -393.5 kJ/mol
C. -590.25 kJ/mol
D. -786.75 kJ/mol
Question 11
A 2.0 M solution of H(NO)( is prepared by dissolving 40.0 g of HNO() in 1.0 L of water. What is the concentration of OH() ions in the solution?
A. 0.02 M
B. 0.04 M
C. 0.06 M
D. 0.08 M
Question 12
The s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. Calculate the s\tandard enthalpy of formation of C2H6(g) if the s\tandard enthalpy of formation of H2(g) is -285.8 kJ/mol.
A. -83.8
B. -85.8
C. -87.8
D. -89.8
Question 13
A 2.0 M solution of HCl is mixed with a 2.0 M solution of NaOH. If the initial concentrations of HCl and NaOH are 2.0 M each, what is the concentration of NaCl that will be formed after the reaction is complete?
A. 2.0 M
B. 1.0 M
C. 0.5 M
D. 0.25 M
Question 14
Determine the number of moles of ΔFe(s) that can be obtained from 2.5 g of Fe(s)(s) u\sing the following reaction: ΔFe(s) + 2H\( + \) → Fe\( 2+ \) + H(2). The molar mass of Fe(s) is 55.85 g/mol.
A. 0.045 mol
B. 0.050 mol
C. 0.055 mol
D. 0.060 mol
Question 15
A sample of a metal has a density of 8.0 g/cm³ and a volume of 10 cm³. If the metal is made of iron (Fe), calculate the mass of the metal in grams.
A. 80 g
B. 80.1 g
C. 80.2 g
D. 80.3 g

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