POST UTME UNIPORT 2021 Chemistry | Objective

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Question 1
A 2.5 M solution of HCl is titrated with 0.1 M NaOH. What is the pH of the solution after 25 mL of NaOH has been added?
A. 1.3
B. 2.3
C. 3.3
D. 4.3
Question 2
Determine the s\tandard electrode potential of the cell represented by the following reaction: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O. Given that the s\tandard electrode potential of MnO4-/Mn2+ is +1.23 V.
A. +1.23 V
B. -1.23 V
C. +1.48 V
D. +2.23 V
Question 3
The s\tandard enthalpy of formation of CO(g) is -110.5 kJ/mol. What is the s\tandard enthalpy of formation of CO2(g)?
A. -393.5 kJ/mol
B. -393.5 kJ/mol
C. -393.5 kJ/mol
D. -393.5 kJ/mol
Question 4
A metal M has a s\tandard electrode potential of +0.5 V. What is the s\tandard electrode potential of the metal ion M^2+?
A. -0.5 V
B. -1.0 V
C. -1.5 V
D. -2.0 V
Question 5
At 25°C, the s\tandard enthalpy of formation of CO2(g) is -393.5 kJ/mol. If 2.5 mol of CO2(g) is produced at cons\tant pressure, what is the change in enthalpy?
A. -987.5 kJ
B. -984.5 kJ
C. -987.0 kJ
D. -984.0 kJ
Question 6
A diagram of a titration setup is shown below. The diagram shows a burette containing a 0.1 M solution of HCl and a flask containing a 0.1 M solution of NaOH. The reaction is: HCl + NaOH → NaCl + H2O. If 25 mL of the HCl solution is added to the flask, what is the resulting pH of the solution?
A. 1
B. 2
C. 3
D. 4
Question 7
The atomic radius of an element is 100 pm. If the element has an atomic number of 20, calculate the number of electrons in a \single atom.
A. 18
B. 20
C. 22
D. 24
Question 8
A polymer has a molecular weight of 100,000 g/mol and a degree of polymerization of 500. Calculate the molar mass of the repeating unit.
A. 100
B. 200
C. 300
D. 400
Question 9
A 2.50-g sample of a non-metallic element, X, reacts with oxygen to form 3.25 g of X2O5. Calculate the empirical formula of X.
A. X2O5
B. XO2
C. XO3
D. XO4
Question 10
A 1.0 M solution of CH3OH is titrated with a 1.0 M solution of HCl. If 20 mL of HCl is required to reach the equivalence point, what is the volume of CH3OH used?
A. 20 mL
B. 40 mL
C. 10 mL
D. 80 mL
Question 11
The rate cons\tant of a reaction is given by the equation: k = Ae^\( -Ea/RT \). If the rate cons\tant at 298 K is 1.5 x 10^\( -3 \) s^\( -1 \), and the activation energy is 50 kJ/mol, what is the value of the pre-exponential factor A?
A. 1.2 x 10^7 s^\( -1 \)
B. 1.5 x 10^7 s^\( -1 \)
C. 2.0 x 10^7 s^\( -1 \)
D. 2.5 x 10^7 s^\( -1 \)
Question 12
A 0.1 M solution of K2Cr2O7 is titrated with a 0.1 M solution of FeSO4. The reaction is: Cr2O72- + 14H+ + 6Fe2+ → 2Cr3+ + 7H2O + 6Fe3+. Calculate the number of moles of Fe2+ required to react with 50 mL of the K2Cr2O7 solution.
A. 0.0025 mol
B. 0.005 mol
C. 0.0075 mol
D. 0.01 mol
Question 13
A 0.1 M solution of NaOH is prepared by dissolving 2.5 g of NaOH in 100 mL of water. What is the molarity of the solution if 2.5 g of NaOH is dissolved in 250 mL of water?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 14
Determine the s\tandard enthalpy of formation of CaCO3(s) from the following data: ΔHf(CaO(s)) = -635.09 kJ/mol, ΔHf(CO2(g)) = -393.51 kJ/mol, ΔHf(C(s)) = 0 kJ/mol.
A. -1206.60 kJ/mol
B. -1206.19 kJ/mol
C. -1206.91 kJ/mol
D. -1207.01 kJ/mol
Question 15
A 2.5 g sample of a metal is dissolved in 50 mL of 0.1 M HCl. What is the molarity of the metal ion in the solution?
A. 0.05 M
B. 0.1 M
C. 0.15 M
D. 0.2 M

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