POST UTME ELIZADE UNIVERSITY 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
Determine the rate cons\tant (k) for the reaction: 2NO(g) + O2(g) → 2NO2(g), 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. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)
B. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
C. \( k = \frac{2.303}{t} \log \frac{[NO]_0 [O_2]_0}{[NO_2]_t} \)
D. \( k = \frac{2.303}{t} \log \frac{[NO_2]_t}{[NO]_0 [O_2]_0} \)
Question 2
A sample of gas occupies a volume of 2.5 L at a temperature of 300 K and a pressure of 1 atm. What is the new volume of the gas when the temperature is increased to 400 K and the pressure is decreased to 0.5 atm?
A. \( V_1 P_1 / T_1 = V_2 P_2 / T_2 \)
B. \( V_1 P_2 / T_2 = V_2 P_1 / T_1 \)
C. \( V_1 P_1 T_2 = V_2 P_2 T_1 \)
D. \( V_1 P_2 T_1 = V_2 P_1 T_2 \)
Question 3
A 2.5 L flask contains 0.15 mol of an ideal gas at 25°C. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.01 atm
B. 1.02 atm
C. 1.03 atm
D. 1.04 atm
Question 4
Calculate the molar mass of a compound that contains 40% carbon, 30% hydrogen, and 30% oxygen by mass.
A. 100
B. 150
C. 200
D. 250
Question 5
A 100 mL sample of a solution containing 0.5 M HCl is titrated with 0.5 M NaOH. What is the volume of NaOH required to reach the equivalence point?
A. 50 mL
B. 75 mL
C. 100 mL
D. 125 mL
Question 6
The diagram below shows a titration setup. Identify the subs\tance being titrated.
A. HCl
B. NaOH
C. H2SO4
D. NH3
Question 7
A 2.5 M solution of NaOH is mixed with a 2.5 M solution of HCl. What is the resulting concentration of the solution?
A. \( C = 2.5 , \text{M} \)
B. \( C = 5.0 , \text{M} \)
C. \( C = 0.0 , \text{M} \)
D. \( C = 1.25 , \text{M} \)
Question 8
Identify the type of polymerization reaction that occurs when a monomer with the molecular formula C5H8 is polymerized in the presence of a catalyst.
A. Addition Polymerization
B. Condensation Polymerization
C. Ring-Opening Polymerization
D. Step-Growth Polymerization
Question 9
The equilibrium cons\tant (Kc) for the reaction: N2(g) + O2(g) ⇌ 2NO(g) is 4.0 × 10^\( -4 \) at 298 K. If the initial concentrations of N2 and O2 are 0.10 M and 0.20 M, respectively, what is the equilibrium concentration of NO(g)?
A. 0.02 M
B. 0.04 M
C. 0.06 M
D. 0.08 M
Question 10
Determine the pH of a 0.1 M solution of acetic acid (CH3COOH) at 25°C, given that the dissociation cons\tant (Ka) of acetic acid is 1.8 × 10^-5.
A. 3.0
B. 3.5
C. 4.0
D. 4.5
Question 11
A sample of nitrogen gas (N2) has a volume of 2.5 liters at a pressure of 750 mmHg and a temperature of 25°C. Calculate the number of moles of nitrogen gas present.
A. 0.05 mol
B. 0.10 mol
C. 0.15 mol
D. 0.20 mol
Question 12
Determine the major product of the reaction between 2-methyl-2-propanol and acetic anhydride.
A. 2-methyl-2-propyl acetate
B. 2-methyl-2-propanol
C. 2-methyl-2-propanone
D. 2-methyl-2-propanoic acid
Question 13
A sample of sulfur (S8) has a mass of 25 grams. Calculate the number of moles of sulfur present.
A. 0.25 mol
B. 0.50 mol
C. 0.75 mol
D. 1.00 mol
Question 14
Determine the pH of a 0.1 M solution of hydrochloric acid (HCl).
A. 1
B. 2
C. 3
D. 4
Question 15
A diagram of the apparatus for the reaction is shown below. Identify the part labeled A.
A. The burette
B. The test tube
C. The thermometer
D. The stirrer

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