POST UTME OSUSTECH 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
The half-reaction: 2H+ + 2e- → H2 has a s\tandard electrode potential of 0 V. What is the s\tandard electrode potential of the reaction: 2H+ + 2e- → H2 + 2H+?
A. 0 V
B. +0.059 V
C. +0.118 V
D. +0.177 V
Question 2
Determine the number of moles of CO2 produced when 2.5 g of C6H12O6 is completely oxidized in the presence of excess O2, given that the balanced equation for the reaction is: C6H12O6 + 6O2 → 6CO2 + 6H2O.
A. 0.05 mol
B. 0.1 mol
C. 0.15 mol
D. 0.2 mol
Question 3
A solution of potassium permanganate (KMnO4) is titrated with a solution of sodium oxalate (Na2C2O4). If 25.0 mL of the permanganate solution is required to react with 20.0 mL of the oxalate solution, what is the concentration of the permanganate solution?
A. 0.10 M
B. 0.20 M
C. 0.30 M
D. 0.40 M
Question 4
Calculate the molarity of a solution containing 25 g of NaOH in 250 mL of water.
A. 0.1 M
B. 0.5 M
C. 1 M
D. 2 M
Question 5
A 1.0 M solution of NH3 is mixed with a 1.0 M solution of HCl in a 1:1 ratio. What is the concentration of the resulting solution?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M
Question 6
A 2.0 L sample of a gas at 27°C and 3 atm is mixed with a 3.0 L sample of a gas at 37°C and 2 atm. What is the final temperature of the mixture in Kelvin?
A. 300 K
B. 310 K
C. 320 K
D. 330 K
Question 7
Identify the type of reaction represented by the equation: \( 2Na + Cl_2 \rightarrow 2NaCl \).
A. Synthesis reaction
B. Decomposition reaction
C. Single displacement reaction
D. Double displacement reaction
Question 8
A 2.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. If the vapor pressure of water at 25°C is 0.0313 atm, calculate the partial pressure of the gas.
A. 0.968 atm
B. 0.980 atm
C. 0.992 atm
D. 1.00 atm
Question 9
The polymerization of styrene to polystyrene involves the addition of a monomer unit to the growing polymer chain. If the rate of polymerization is 0.05 mol/L·min, and the initial concentration of styrene is 1.0 mol/L, what is the concentration of styrene after 10 minutes?
A. 0.95 mol/L
B. 0.90 mol/L
C. 0.85 mol/L
D. 0.80 mol/L
Question 10
A sample of a polymer has a molecular weight of 50000 g/mol. If 0.5 g of the polymer is dissolved in 100 mL of solvent, what is the concentration of the solution in g/L?
A. 0.05 g/L
B. 0.5 g/L
C. 5 g/L
D. 50 g/L
Question 11
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 1.0 L of water. What is the concentration of Cl^- ions in the solution?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M
Question 12
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g) at 298 K, given that the initial concentrations of NO and O2 are 0.1 M and 0.2 M, respectively, and the rate of reaction is 0.05 M/s after 10 minutes.
A. \( 2.5 \times 10^{-3} , \text{s}^{-1} \)
B. \( 5.0 \times 10^{-3} , \text{s}^{-1} \)
C. \( 1.0 \times 10^{-2} , \text{s}^{-1} \)
D. \( 2.0 \times 10^{-2} , \text{s}^{-1} \)
Question 13
A gas sample is collected over water at a temperature of 25°C and a pressure of 1.0 atm. If the partial pressure of the gas is 0.8 atm, what is the mole \fraction of the gas?
A. 0.80
B. 0.85
C. 0.90
D. 0.95
Question 14
At 25°C, 1.00 L of an ideal gas at 2.00 atm exerts a pressure of 2.00 atm. What is the volume of the gas at 4.00 atm and 25°C?
A. 0.500 L
B. 1.00 L
C. 2.00 L
D. 4.00 L
Question 15
A sample of an ideal gas at 25°C and 1 atm expands from 2.0 L to 4.0 L. Calculate the work done by the gas in Joules.
A. 40 J
B. 80 J
C. 120 J
D. 160 J

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