POST UTME UNN 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 10 g sample of a subs\tance is burned in a bomb calorimeter, relea\sing 2500 J of heat. If the heat capacity of the calorimeter is 1000 J/K, what is the change in internal energy (ΔU) of the subs\tance?
A. -2500 J
B. -2000 J
C. -1500 J
D. -1000 J
Question 2
The diagram below shows a titration setup. What is the purpose of the burette?
A. To measure the volume of the titrant.
B. To measure the volume of the analyte.
C. To mix the titrant and analyte.
D. To measure the pH of the solution.
Question 3
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of hydrogen gas (H2) react with oxygen gas according to the equation: 2H2 + O2 → 2H2O.
A. 1.25 moles
B. 2.5 moles
C. 3.75 moles
D. 5 moles
Question 4
A sample of oxygen gas at 25°C and 1 atm is compressed to a final pressure of 5 atm. What is the final temperature of the gas?
A. 50°C
B. 75°C
C. 100°C
D. 125°C
Question 5
A voltaic cell consists of a zinc anode and a copper cathode. If the s\tandard reduction potential of zinc is -0.76 V and the s\tandard reduction potential of copper is +0.34 V, what is the cell potential?
A. -1.1 V
B. -0.9 V
C. -0.7 V
D. -0.5 V
Question 6
A 0.1 M solution of a weak acid HA is 5% ionized at 25°C. Calculate the pH of the solution.
A. 2.3
B. 2.5
C. 2.7
D. 2.9
Question 7
A 2.5 M solution of HCl is mixed with a 1.5 M solution of NaOH. What is the concentration of the resulting solution?
A. 1.5 M
B. 2.5 M
C. 3.5 M
D. 4.5 M
Question 8
The diagram below shows a simple black and white chemistry apparatus showing a titration setup. What is the purpose of the burette?
A. To measure the volume of the titrant.
B. To measure the volume of the analyte.
C. To mix the titrant and analyte.
D. To measure the pH of the solution.
Question 9
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 10
The solubility of a gas in a liquid is influenced by the following factors: temperature, pressure, and the nature of the gas and liquid. Which of the following statements is NOT true about the solubility of a gas in a liquid?
A. The solubility of a gas in a liquid increases with increa\sing temperature.
B. The solubility of a gas in a liquid decreases with increa\sing pressure.
C. The solubility of a gas in a liquid is indep\endent of the nature of the gas and liquid.
D. The solubility of a gas in a liquid increases with increa\sing pressure.
Question 11
A 10.0 mL sample of a 0.100 M solution of NaOH is mixed with 10.0 mL of a 0.100 M solution of HCl. What is the pH of the resulting solution?
A. 7.00
B. 7.00
C. 7.00
D. 7.00
Question 12
A sample of a polymer has a molecular weight of 100,000 g/mol. If the polymer is composed of 80% monomer A and 20% monomer B, what is the average molecular weight of the polymer?
A. 80,000 g/mol
B. 90,000 g/mol
C. 100,000 g/mol
D. 110,000 g/mol
Question 13
The reaction between chlorine gas and potassium iodide is a classic example of a redox reaction. Write the balanced chemical equation for this reaction, including the states of matter for each reac\tant and product.
A. Cl2(g) + 2KI(s) → 2KCl(s) + I2(s)
B. Cl2(g) + 2KI(s) → 2KCl(s) + I2(g)
C. Cl2(g) + 2KI(l) → 2KCl(l) + I2(g)
D. Cl2(l) + 2KI(s) → 2KCl(s) + I2(g)
Question 14
A 1.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. The vapor pressure of water at 25°C is 23.8 mmHg. What is the partial pressure of the gas?
A. 0.976 atm
B. 0.976 atm
C. 0.976 atm
D. 0.976 atm
Question 15
The atomic radius of a metal atom is 200 pm. If the metal atom has a valency of 2, what is the expected value of the atomic radius of its monovalent ion?
A. 180 pm
B. 220 pm
C. 240 pm
D. 260 pm

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