POST UTME AL-HIKMAH UNIVERSITY 2021 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 L flask contains 0.5 mol of $\text{O}_2$ at 25°C. What is the partial pressure of $\text{O}_2$ in the flask?
A. 0.5 atm
B. 1 atm
C. 2 atm
D. 5 atm
Question 2
The half-reaction Zn → Zn2+ + 2e- has a s\tandard electrode potential of -0.76 V. What is the s\tandard electrode potential for the reaction Zn2+ + 2e- → Zn?
A. 0.76 V
B. -0.76 V
C. 1.52 V
D. -1.52 V
Question 3
The half-life of a radioactive subs\tance is 10 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 30 years?
A. 12.5 g
B. 25 g
C. 50 g
D. 100 g
Question 4
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 disappearance of NO is 0.05 M/s after 10 minutes.
A. 0.05 min^-1
B. 0.1 min^-1
C. 0.2 min^-1
D. 0.3 min^-1
Question 5
Determine the number of moles of acetic acid (CH3COOH) that can be obtained from 250 mL of a 0.5 M solution of sodium acetate (CH3COONa) when it is mixed with 100 mL of 1 M hydrochloric acid (HCl).
A. 0.125 mol
B. 0.25 mol
C. 0.5 mol
D. 1 mol
Question 6
The s\tandard electrode potential for the reaction Zn2+ + 2e- → Zn is -0.76 V. What is the s\tandard electrode potential for the reaction Zn → Zn2+ + 2e-?
A. 0.76 V
B. -0.76 V
C. 1.52 V
D. -1.52 V
Question 7
The half-life of a radioactive subs\tance is 5.0 years. If 100 g of the subs\tance initially decays to 50 g, how many years will it take for the subs\tance to decay to 25 g?
A. 10 years
B. 15 years
C. 20 years
D. 25 years
Question 8
The s\tandard electrode potential for the reaction Zn2+ + 2e- → Zn is -0.76 V. What is the s\tandard electrode potential for the reaction Zn → Zn2+ + 2e-?
A. 0.76 V
B. -0.76 V
C. 1.52 V
D. -1.52 V
Question 9
A 2.0 L flask contains 0.5 mol of an ideal gas at 300 K. Calculate the work done by the gas when it expands from 2.0 L to 4.0 L against a cons\tant external pressure of 1.0 atm.
A. 2.0 J
B. 4.0 J
C. 6.0 J
D. 8.0 J
Question 10
A 0.5 M solution of HCl is mixed with a 0.5 M solution of NaOH. What is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 11
A 2.5 L flask contains 0.25 mol of an ideal gas at 298 K. Calculate the pressure of the gas u\sing the ideal gas law.
A. 1.01 × 10^5 Pa
B. 2.02 × 10^5 Pa
C. 3.03 × 10^5 Pa
D. 4.04 × 10^5 Pa
Question 12
A 2.0 g sample of a polymer is dissolved in 100 mL of a solvent. If the density of the solution is 1.2 g/mL, what is the molar mass of the polymer?
A. 100 g/mol
B. 200 g/mol
C. 500 g/mol
D. 1000 g/mol
Question 13
A 2.5 L flask contains 0.5 mol of $\text{O}_2$ at 25°C. What is the partial pressure of $\text{O}_2$ in the flask?
A. 0.5 atm
B. 1 atm
C. 2 atm
D. 5 atm
Question 14
A solution contains 2.5 g of $\text{NaCl}$ per 100 mL of solution. What is the molarity of the solution?
A. 0.1 M
B. 0.2 M
C. 0.5 M
D. 1 M
Question 15
Determine the s\tandard Gibbs free energy change for the reaction: 2Ag+(aq) + 2Cl-(aq) → 2AgCl(s) at 298 K.
A. -120 kJ/mol
B. -240 kJ/mol
C. -300 kJ/mol
D. -400 kJ/mol

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