POST UTME UNILAG 2023 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A metal M has a crystal structure with a lattice parameter of 3.5 Å. If the metal has a density of 8.9 g/cm³, calculate the number of atoms per unit cell.
A. 4
B. 6
C. 8
D. 10
Question 2
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH, what is the number of moles of HCl that react with NaOH?
A. 0.0025 mol
B. 0.0026 mol
C. 0.0027 mol
D. 0.0028 mol
Question 3
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4
Question 4
A sample of Fe2O3 is heated in a Bunsen burner flame. What is the color of the flame?
A. Green
B. Blue
C. Red
D. Yellow
Question 5
The s\tandard Gibbs free energy change \( ΔG^circ \) for the reaction: 2NO(g) + O2(g) → 2NO2(g) at 298 K is -114.1 kJ/mol. Calculate the equilibrium cons\tant (K) for the reaction.
A. 1.1 × 10^5
B. 1.1 × 10^5
C. 1.1 × 10^5
D. 1.1 × 10^5
Question 6
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the number of moles of HCl that react with NaOH.
A. 0.0025 mol
B. 0.0026 mol
C. 0.0027 mol
D. 0.0028 mol
Question 7
A diagram of a titration setup is shown below. If 25.0 mL of 0.100 M HCl is titrated with 0.100 M NaOH, what is the pH of the solution after the addition of 25.0 mL of NaOH?
A. 2.00
B. 2.50
C. 3.00
D. 3.50
Question 8
A 1.0 M solution of H2SO4 is titrated with a 1.0 M solution of NaOH. What is the pH of the solution after 50 mL of NaOH has been added?
A. 1
B. 2
C. 3
D. 4
Question 9
A solution of NaCl is prepared by dissolving 35.5 g of NaCl in 250 cm³ of water. Calculate the molarity of the solution.
A. 0.15 M
B. 0.25 M
C. 0.35 M
D. 0.45 M
Question 10
The rate cons\tant (k) of a first-order reaction is given by the equation: k = Ae^\( -Ea/RT \). If the activation energy (Ea) is 100 kJ/mol, the gas cons\tant (R) is 8.314 J/mol*K, and the temperature (T) is 300 K, calculate the value of k when A = 2.5 x 10^\( -3 \) s^\( -1 \).
A. 1.5 x 10^\( -3 \) s^\( -1 \)
B. 2.5 x 10^\( -3 \) s^\( -1 \)
C. 3.5 x 10^\( -3 \) s^\( -1 \)
D. 4.5 x 10^\( -3 \) s^\( -1 \)
Question 11
The rate of a chemical reaction is affected by the concentration of the reac\tants. Which of the following statements is TRUE about the relationship between concentration and rate?
A. Increa\sing concentration increases the rate of reaction.
B. Decrea\sing concentration decreases the rate of reaction.
C. Concentration has no effect on the rate of reaction.
D. Increa\sing concentration decreases the rate of reaction.
Question 12
A sample of CO2 gas occupies a volume of 2.5 dm³ at a pressure of 1.5 atm. Calculate the number of moles of CO2 present.
A. 0.05 mol
B. 0.10 mol
C. 0.15 mol
D. 0.20 mol
Question 13
A solution of HCl is prepared by dissolving 25 g of HCl in 100 cm³ of water. Calculate the concentration of the solution in terms of molarity.
A. 1.0 M
B. 2.0 M
C. 3.0 M
D. 4.0 M
Question 14
A solution contains 0.1 M NaCl and 0.2 M NaNO3. 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 15
The reaction between sodium and chlorine to form sodium chloride is an example of a ______________ reaction.
A. synthesis
B. decomposition
C. replacement
D. combustion

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