POST UTME UNIPORT 2021 Chemistry | Objective

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Question 1
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 2
A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2MO3. If 3.2 g of M is heated in air, what is the mass of MO3 formed?
A. 6.4 g
B. 8.0 g
C. 9.6 g
D. 12.8 g
Question 3
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 4
A metal (M) reacts with oxygen to form a basic oxide. The reaction is as follows: 4M + 3O2 → 2MO3. If 3.2 g of M is heated in air, what is the volume of O2 consumed at STP?
A. 2.4 L
B. 2.8 L
C. 3.2 L
D. 1.6 L
Question 5
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 6
A 0.5 M solution of HCl is titrated with a 0.5 M solution of NaOH. If 25 mL of NaOH is required to reach the equivalence point, what is the volume of HCl used?
A. 25 mL
B. 50 mL
C. 12.5 mL
D. 62.5 mL
Question 7
A metal, M, has an atomic radius of 0.200 nm and an electron affinity of -3.00 eV. Calculate the ionization energy of M.
A. -3.00 eV
B. -2.00 eV
C. -1.00 eV
D. 0.00 eV
Question 8
A sample of $CaCO_3$ is heated in a crucible until it decomposes completely. The mass of the crucible and its contents before heating is 50.0 g, and the mass after heating is 45.0 g. What is the mass of $CO_2$ produced during the decomposition?
A. 2.00 g
B. 4.00 g
C. 6.00 g
D. 8.00 g
Question 9
A solution of $H_2SO_4$ is prepared by dissolving $H_2SO_4(s)$ in water. The resulting solution is found to be 0.25 M in $H_2SO_4$. What is the concentration of $H^+$ ions in the solution?
A. 0.25 M
B. 0.50 M
C. 0.75 M
D. 1.00 M
Question 10
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 11
A 0.1 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 100 mL of water. What is the molarity of the solution if 2.5 g of NaCl is dissolved in 250 mL of water?
A. 0.1 M
B. 0.2 M
C. 0.3 M
D. 0.4 M
Question 12
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 13
A metal M has a density of 8 g/cm^3. What is the volume of 100 g of the metal?
A. 12.5 cm^3
B. 15.0 cm^3
C. 17.5 cm^3
D. 20.0 cm^3
Question 14
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 15
The rate cons\tant of a first-order reaction is 0.05 min^\( -1 \). If the initial concentration of the reac\tant is 0.1 M, calculate the concentration after 10 minutes.
A. 0.05
B. 0.1
C. 0.2
D. 0.3

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