POST UTME UNN 2025 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 2.5 M solution of sodium hydroxide is prepared by dissolving 12.5 g of NaOH in water to make 1 L of solution. What is the concentration of the solution in moles per liter?
A. 2.5 M
B. 5 M
C. 10 M
D. 12.5 M
Question 2
A metal alloy consists of 75% copper and 25% zinc. If 2.5 kg of the alloy is melted and cast into a cylindrical shape, what is the volume of the cylinder?
A. \( 2.5 , \text{kg} \times 0.75 \times 8.9 , \text{g/cm}^3 \)
B. \( 2.5 , \text{kg} \times 0.75 \times 8.9 , \text{g/cm}^3 \times 1000 , \text{cm}^3/\text{L} \)
C. \( 2.5 , \text{kg} \times 0.75 \times 8.9 , \text{g/cm}^3 \times 1000 , \text{cm}^3/\text{L} \times pi , \text{r}^2 \)
D. \( 2.5 , \text{kg} \times 0.75 \times 8.9 , \text{g/cm}^3 \times 1000 , \text{cm}^3/\text{L} \times pi , \text{r}^2 \times 2 , \text{cm} \)
Question 3
A 2 L solution of 0.2 M H2SO4 is prepared by dissolving 40 g of H2SO4 in water. What is the concentration of the solution in moles per liter?
A. 0.2 M
B. 0.4 M
C. 0.6 M
D. 0.8 M
Question 4
A 1.0 g sample of sulfur is burned in a bomb calorimeter and releases 2000 J of heat. If the heat of combustion of sulfur is 1000 J/g, what is the percentage yield of sulfur?
A. 50
B. 60
C. 70
D. 80
Question 5
A 2.50 g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 1.75 g, what is the molar mass of the metal carbonate?
A. 100 g/mol
B. 150 g/mol
C. 200 g/mol
D. 250 g/mol
Question 6
The reaction between chlorine gas and potassium iodide is a classic example of a redox reaction. What is the oxidation state of iodine in KI?
A. 0
B. -1
C. +1
D. +2
Question 7
A 1.00 g sample of a compound containing only C, H, and O is analyzed by combustion and found to produce 0.500 g of CO2 and 0.250 g of H2O. What is the empirical formula of the compound?
A. C2H4O
B. C2H4O
C. C2H4O
D. C2H4O
Question 8
A sample of air is collected over water and has a volume of 1.5 L at 25°C and 1 atm. If the partial pressure of water vapor is 0.03 atm, what is the mole \fraction of water vapor in the air?
A. 0.02
B. 0.04
C. 0.06
D. 0.08
Question 9
Determine the pH of a 0.1 M solution of HCl at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the temperature dep\endence of the dissociation cons\tant is described by the equation \( \log_{10} K = -\frac{1000}{2.303RT} \), where R is the gas cons\tant and T is the temperature in Kelvin.
A. 1
B. 2
C. 3
D. 4
Question 10
Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data:\n\nΔHf(CaO(s)) = -635.09 kJ/mol\nΔHf(CO2(g)) = -393.51 kJ/mol\nΔHf(Ca(s)) = -178.2 kJ/mol
A. -1206.79 kJ/mol
B. -1206.79 kJ/mol
C. -1206.79 kJ/mol
D. -1206.79 kJ/mol
Question 11
A diagram of a titration setup is shown below. If 25.0 mL of 0.1 M NaOH is required to reach the equivalence point, what is the concentration of the HCl solution?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.5 M
Question 12
A sample of a metal oxide has a mass of 25 g and a volume of 2.5 cm3. What is the density of the metal oxide?
A. \( 10 , \text{g/cm}^3 \)
B. \( 20 , \text{g/cm}^3 \)
C. \( 30 , \text{g/cm}^3 \)
D. \( 40 , \text{g/cm}^3 \)
Question 13
A 1 L solution of 0.5 M NaCl is prepared by dissolving 25 g of NaCl in water. What is the concentration of the solution in moles per liter?
A. 0.5 M
B. 1 M
C. 2 M
D. 5 M
Question 14
A 2.50 M solution of HCl is mixed with a 1.00 M solution of NaOH. If the reaction is allowed to go to completion, what is the concentration of the resulting solution?
A. 1.75 M
B. 2.25 M
C. 2.50 M
D. 3.75 M
Question 15
A 1.0 M solution of NaOH is titrated with a 1.0 M solution of HCl. If 25 mL of HCl is required to reach the equivalence point, what is the volume of NaOH required to reach the equivalence point?
A. 25
B. 50
C. 75
D. 100

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