POST UTME UNIPORT 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A 0.1 M solution of $NaOH$ is mixed with a 0.1 M solution of $HCl$. The resulting solution is then electrolyzed u\sing a platinum electrode.
A. The resulting solution will be a strong base.
B. The resulting solution will be a weak base.
C. The resulting solution will be a strong acid.
D. The resulting solution will be a weak acid.
Question 2
The atomic radius of an element is 100 pm. If the element has an electron configuration of [Ar] 4s^(2) 3d^(5), what is the expected oxidation state of the element?
A. +2
B. +3
C. +5
D. +7
Question 3
A 2.5 L sample of a gas at 27°C and 1 atm is compressed to 1 L at 127°C. Calculate the work done on the gas, assuming it behaves as an ideal gas.
A. -2.5 kJ
B. -5.0 kJ
C. -7.5 kJ
D. -10.0 kJ
Question 4
A 2.50-g sample of a metal carbonate is heated to produce a metal oxide and carbon dioxide gas. If the mass of the metal oxide produced is 1.75 g, calculate the percentage yield of the metal oxide.
A. 75%
B. 80%
C. 85%
D. 90%
Question 5
Determine the molar solubility of Ag2CrO4 in 0.1 M NaCl solution, given that the solubility product cons\tant (Ksp) for Ag2CrO4 is 1.1 × 10^\( -12 \).
A. 1.0 × 10^\( -5 \) M
B. 1.0 × 10^\( -6 \) M
C. 1.0 × 10^\( -7 \) M
D. 1.0 × 10^\( -8 \) M
Question 6
A 2.5 M solution of H2SO4 is electrolyzed u\sing a platinum electrode. Calculate the mass of oxygen gas collected at the anode after 2 hours, given that the current is 5 A and the cell potential is 2.0 V.
A. 0.15 g
B. 0.20 g
C. 0.25 g
D. 0.30 g
Question 7
A sample of a metal (M) reacts with hydrochloric acid (HCl) to produce hydrogen gas. The reaction is represented by the equation: M + 2HCl → MCl2 + H2. If 2.5 g of the metal is reacted with 20 mL of 1 M HCl, what is the volume of hydrogen gas produced at STP?
A. 10 mL
B. 20 mL
C. 30 mL
D. 40 mL
Question 8
The rate cons\tant (k) of a first-order reaction is related to the half-life \( t_\( 1/2 \ \)) by the equation: \( k = \frac{ln 2}{t_{1/2}} \). If the half-life of a reaction is 10 minutes, what is the rate cons\tant (k) in min^\( -1 \)?
A. 0.0693 min^\( -1 \)
B. 0.693 min^\( -1 \)
C. 6.93 min^\( -1 \)
D. 69.3 min^\( -1 \)
Question 9
A 10.0-mL sample of a solution containing 0.050 M NaOH is mixed with 10.0 mL of a solution containing 0.050 M HCl. Calculate the pH of the resulting solution.
A. 1.00
B. 2.00
C. 3.00
D. 4.00
Question 10
A solution containing 0.1 M CuSO4 is mixed with a solution containing 0.1 M Na2S. Calculate the number of moles of CuS formed.
A. 0.005 mol
B. 0.01 mol
C. 0.015 mol
D. 0.02 mol
Question 11
A solution containing 0.1 M CuSO4 is mixed with a solution containing 0.1 M Na2S. Calculate the number of moles of CuS formed.
A. 0.005 mol
B. 0.01 mol
C. 0.015 mol
D. 0.02 mol
Question 12
The equilibrium cons\tant \( K_\( c \ \)) for the reaction: \( N_2O_4 \rightleftharpoons 2NO_2 \) is 1.8 × 10^\( -3 \) at 298 K. If the initial concentration of N_(2)O_(4) is 0.1 M, what is the concentration of NO_(2) at equilibrium?
A. 0.0015 M
B. 0.015 M
C. 0.15 M
D. 1.5 M
Question 13
A metal (M) reacts with oxygen to form a metal oxide (MO). The balanced equation for the reaction is: 4M + 3O_2 \rightarrow 2MO. If 2.50 g of the metal (M) is heated in air, and 1.75 g of the metal oxide (MO) is produced, calculate the percentage yield of the metal oxide.
A. 70%
B. 75%
C. 80%
D. 85%
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.
A. -1785.6 kJ/mol
B. -1785.9 kJ/mol
C. -1786.1 kJ/mol
D. -1786.3 kJ/mol
Question 15
A 1.0 M solution of H2SO4 is mixed with a 1.0 M solution of NaOH. What is the resulting concentration of H+ ions?
A. 0.5 M
B. 1.0 M
C. 1.5 M
D. 2.0 M

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