POST UTME BOWEN UNIVERSITY 2018 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A sample of a polymer has a molecular weight of 10,000 g/mol. If the polymer has a degree of polymerization (DP) of 50, what is the molecular weight of the repeating unit?
A. 200 g/mol
B. 10 g/mol
C. 50 g/mol
D. 25 g/mol
Question 2
A solution contains 0.5 M HCl and 0.5 M NaOH. What is the concentration of H+ ions in the solution after mixing?
A. 0.5 M
B. 1.0 M
C. 0.25 M
D. 0.75 M
Question 3
A reaction is carried out at cons\tant pressure and temperature. The reaction is exothermic and has a negative ΔH value. Which of the following statements is correct?
A. The reaction is spon\taneous.
B. The reaction is non-spon\taneous.
C. The reaction is at equilibrium.
D. The reaction has a positive ΔS value.
Question 4
The s\tandard Gibbs free energy change for the reaction 2Ag+(aq) + 2e- → Ag(s) is -0.80 V. What is the equilibrium cons\tant (K) for the reaction?
A. 10^\( -0.80 \)
B. 10^0.80
C. 10^\( -1.60 \)
D. 10^1.60
Question 5
A solution contains 0.5 M NaCl. If 10 mL of this solution is diluted to 100 mL, what is the concentration of the resulting solution?
A. 0.05 M
B. 0.5 M
C. 1 M
D. 5 M
Question 6
Calculate the s\tandard enthalpy change (ΔH) for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that the s\tandard enthalpy of formation (ΔHf) for Al2O3(s) is -1675.7 kJ/mol, and the s\tandard enthalpy of formation for Fe(s) is 0 kJ/mol. The s\tandard enthalpy of formation for Al(s) is 0 kJ/mol, and for Fe2O3(s) is -826.4 kJ/mol.
A. -1651.1 kJ/mol
B. -1675.7 kJ/mol
C. -826.4 kJ/mol
D. -1651.1 kJ/mol + 826.4 kJ/mol
Question 7
Determine the number of moles of oxygen gas (O2) required to react with 2.5 moles of carbon monoxide (CO) in the following equation: 2CO + O2 → 2CO2.
A. 1.25 moles
B. 2.5 moles
C. 5 moles
D. 10 moles
Question 8
A 2.5 M solution of sodium hydroxide (NaOH) is mixed with a 1.0 M solution of hydrochloric acid (HCl). What is the resulting concentration of the solution?
A. 1.5 M
B. 2.0 M
C. 2.5 M
D. 3.0 M
Question 9
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, what is the value of the rate cons\tant (k) if the pre-exponential factor (A) is 1.0 x 10^10 s^\( -1 \)?
A. 1.0 x 10^\( -4 \) s^\( -1 \)
B. 1.0 x 10^\( -3 \) s^\( -1 \)
C. 1.0 x 10^\( -2 \) s^\( -1 \)
D. 1.0 x 10^\( -1 \) s^\( -1 \)
Question 10
The half-life of a radioactive subs\tance is 5.30 days. If the initial amount of the subs\tance is 100 mg, what is the amount remaining after 21.5 days?
A. 12.5 mg
B. 25.0 mg
C. 37.5 mg
D. 50.0 mg
Question 11
A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in 100 mL of water. What is the concentration of the solution in mol/L?
A. 1.0 M
B. 2.0 M
C. 3.0 M
D. 4.0 M
Question 12
A sample of a polymer has a molecular weight of 50,000 g/mol. If the polymer has a degree of polymerization (DP) of 200, what is the molecular weight of the repeating unit?
A. 250 g/mol
B. 50 g/mol
C. 200 g/mol
D. 100 g/mol
Question 13
A solution contains 0.1 M HCl and 0.1 M NaOH. What is the concentration of H+ ions in the solution after mixing?
A. 0.1 M
B. 0.2 M
C. 0.05 M
D. 0.15 M
Question 14
The s\tandard enthalpy of formation of NH3(g) is -45.9 kJ/mol. Calculate the s\tandard enthalpy of combustion of 1 mole of ammonia at 298 K.
A. -45.9 kJ
B. -45.9 kJ/mol
C. -45.9 kJ/g
D. -45.9 kJ/mol NH_3(g)
Question 15
A 1.00-g sample of a non-metallic element is burned in oxygen to produce 1.80 g of the oxide. What is the empirical formula of the oxide?
A. SO2
B. SO3
C. SO4
D. SO5

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