POST UTME OAU 2020 Chemistry | Objective

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Question 1
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 25.0 mL of NaOH has been added?
A. \( pH = 7 \)
B. \( pH = 3 \)
C. \( pH = 10 \)
D. \( pH = 12 \)
Question 2
A solution contains 2.5 g of sodium chloride (NaCl) dissolved in 100.0 mL of water. Calculate the molarity of the solution.
A. 0.25 M
B. 0.50 M
C. 1.0 M
D. 1.5 M
Question 3
A sample of gas has a volume of 2.5 L at a pressure of 1.5 atm and a temperature of 25°C. If the pressure is increased to 3.0 atm and the temperature is increased to 50°C, calculate the new volume of the gas.
A. 3.0 L
B. 4.0 L
C. 5.0 L
D. 6.0 L
Question 4
A 2.0 M solution of NaOH is prepared by dissolving 40 g of NaOH in 1 L of water. Calculate the concentration of the solution in mol/L.
A. 2.0 M
B. 1.0 M
C. 3.0 M
D. 4.0 M
Question 5
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 25.0 mL of NaOH has been added?
A. \( pH = 7 \)
B. \( pH = 3 \)
C. \( pH = 10 \)
D. \( pH = 12 \)
Question 6
A 1.5 M solution of HCl is prepared by dissolving 45 g of HCl in 1 L of water. Calculate the concentration of the solution in mol/L.
A. 1.5 M
B. 0.5 M
C. 2.5 M
D. 3.5 M
Question 7
Determine the number of moles of oxygen gas (O2) produced at STP when 2.5 moles of potassium chlorate (KClO3) decompose according to the equation: 2KClO3(s) → 2KCl(s) + 3O2(g).
A. 1.5 moles
B. 2.5 moles
C. 3.75 moles
D. 4.5 moles
Question 8
A sample of air contains 20% oxygen, 70% nitrogen, and 10% other gases. If the total pressure of the air is 1 atm, what is the partial pressure of oxygen?
A. 0.2 atm
B. 0.4 atm
C. 0.6 atm
D. 0.8 atm
Question 9
A 50.0 mL sample of a 0.100 M solution of NaOH is mixed with 50.0 mL of a 0.100 M solution of HCl. What is the pH of the resulting solution?
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 10
A polymer is formed by the condensation reaction of 1 mole of ethylene glycol with 1 mole of terephthalic acid. If the molecular weight of the polymer is 200 g/mol, what is the degree of polymerization?
A. 2
B. 4
C. 6
D. 8
Question 11
The half-life of a radioactive subs\tance is 10 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 20 years?
A. 50 g
B. 25 g
C. 12.5 g
D. 6.25 g
Question 12
A 1.0 M solution of FeSO4 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 1 hour, and the current is 0.2 A, calculate the mass of iron deposited at the cathode.
A. 0.5 g
B. 1.0 g
C. 2.0 g
D. 3.0 g
Question 13
A 2.5 M solution of HCl is titrated with 0.5 M NaOH. If 40 mL of NaOH is required to reach the equivalence point, calculate the volume of HCl required to reach the equivalence point.
A. 80 mL
B. 100 mL
C. 120 mL
D. 140 mL
Question 14
A 1.5 M solution of CuSO4 is electrolyzed u\sing a platinum electrode. If the electrolysis is carried out for 2 hours, and the current is 0.3 A, calculate the mass of copper deposited at the cathode.
A. 1.0 g
B. 2.0 g
C. 3.0 g
D. 4.0 g
Question 15
A solution of NaOH is prepared by dissolving 50.0 g of NaOH in 100.0 mL of water. What is the molarity of the solution?
A. 0.5 M
B. 1.0 M
C. 2.0 M
D. 5.0 M

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