POST UTME LASU 2017 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 10.0 g sample of a non-metallic element is heated in a stream of oxygen gas. If 11.2 g of the oxide is formed, what is the empirical formula of the oxide?
A. P2O5
B. SO2
C. Cl2O7
D. Br2O7
Question 2
A solution of 0.100 M NaOH is mixed with a solution of 0.100 M HCl. What is the pH of the resulting solution?
A. 7.00
B. 6.00
C. 5.00
D. 4.00
Question 3
The half-life of a radioactive subs\tance is 10 years. If 100 g of the subs\tance is present initially, what is the mass of the subs\tance remaining after 30 years?
A. 6.25 g
B. 12.5 g
C. 25.0 g
D. 50.0 g
Question 4
At 298 K, the equilibrium cons\tant (Kc) for the reaction N2O4(g) ⇌ 2NO2(g) is 1.8 × 10^\( -2 \). Calculate the equilibrium cons\tant (Kp) for the reaction at the same temperature.
A. 1.8 × 10^\( -1 \)
B. 1.8 × 10^\( -2 \)
C. 1.8 × 10^\( -3 \)
D. 1.8 × 10^\( -4 \)
Question 5
The half-life of a radioactive subs\tance is 5 days. If 100 mg of the subs\tance is initially present, how much of the subs\tance will remain after 20 days?
A. 12.5 mg
B. 25 mg
C. 50 mg
D. 100 mg
Question 6
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 25 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 7
The rate cons\tant for a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 8
A 2.0 M solution of H2SO4 is mixed with a 1.0 M solution of NaOH. Calculate the pH of the resulting solution after the reaction is complete.
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 9
A sample of a non-metallic oxide has a mass of 25.0 g and a volume of 5.00 cm³. What is the molar mass of the oxide?
A. 50.0 g/mol
B. 100.0 g/mol
C. 150.0 g/mol
D. 200.0 g/mol
Question 10
A solution contains 0.1 M HCl. If 50.0 mL of 0.1 M NaOH is added to 100.0 mL of the solution, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 11
A 100.0 mL sample of a solution containing 0.100 M NaOH is mixed with 100.0 mL of a solution containing 0.100 M HCl. What is the pH of the resulting solution?
A. 7.00
B. 6.00
C. 5.00
D. 4.00
Question 12
The s\tandard enthalpy of formation (ΔHf) for the reaction C(s) + O2(g) → CO2(g) is -393.5 kJ/mol. What is the s\tandard enthalpy of formation (ΔHf) for the reaction C(s) + 2H2(g) → CH4(g)?
A. -74.8 kJ/mol
B. -74.9 kJ/mol
C. -75.0 kJ/mol
D. -75.1 kJ/mol
Question 13
A metal M has a s\tandard electrode potential of +0.5 V. If a solution contains 0.1 M M2+ ions, what is the concentration of M that can be reduced at the cathode?
A. 0.01 M
B. 0.02 M
C. 0.03 M
D. 0.04 M
Question 14
A 25.0 mL sample of a solution containing 0.100 M KI is mixed with 25.0 mL of a solution containing 0.100 M AgNO3. What is the concentration of the resulting solution?
A. 0.0500 M
B. 0.100 M
C. 0.200 M
D. 0.500 M
Question 15
A 1.00-mol sample of a gas is confined to a 2.00-L container at a temperature of 298 K. What is the pressure of the gas in atm?
A. 0.500 atm
B. 1.00 atm
C. 1.50 atm
D. 2.00 atm

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