POST UTME UNIPORT 2022 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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 2
The solubility product cons\tant \( K_\( sp \ \)) of AgCl is 1.8 × 10^\( -10 \) at 298 K. If the concentration of Ag^\( + \) is 0.01 M, what is the concentration of Cl^\( - \) at equilibrium?
A. 1.8 × 10^\( -9 \) M
B. 1.8 × 10^\( -10 \) M
C. 1.8 × 10^\( -11 \) M
D. 1.8 × 10^\( -12 \) M
Question 3
The rate cons\tant (k) for a first-order reaction is given by the equation: k = 2.303 \frac{\text{\log}\( a/x \)}{t} where a is the initial concentration and x is the concentration at time t. If the initial concentration of a reac\tant is 0.100 M and the concentration at time t is 0.050 M, calculate the rate cons\tant (k) if the time (t) is 10 minutes.
A. 0.010 min^{-1}
B. 0.020 min^{-1}
C. 0.030 min^{-1}
D. 0.040 min^{-1}
Question 4
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 5
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 6
A 0.5 M solution of NaOH is mixed with a 0.5 M solution of HCl. What is the pH of the resulting solution?
A. 7.0
B. 8.0
C. 9.0
D. 10.0
Question 7
A 1 L solution of $H_2SO_4$ is electrolyzed u\sing a platinum electrode. The anode reaction is $2H_2O(l) \rightarrow O_2(g) + 4H^+(aq) + 4e^-$.
A. The anode potential is more negative than the cathode potential.
B. The anode potential is more positive than the cathode potential.
C. The anode reaction is a reduction reaction.
D. The anode reaction is an oxidation reaction.
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 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 10
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
Question 11
A 2.0 M solution of HCl is electrolyzed u\sing a platinum electrode. Calculate the mass of chlorine gas collected at the anode after 1 hour, given that the current is 3 A and the cell potential is 1.5 V.
A. 0.10 g
B. 0.15 g
C. 0.20 g
D. 0.25 g
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 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 14
A 0.5 M solution of NH3 is mixed with a 0.5 M solution of HCl. What is the resulting pH?
A. 7.0
B. 8.0
C. 9.0
D. 10.0
Question 15
A 25.0-mL sample of a solution containing 0.100 M Fe^{2+} ions is mixed with 25.0 mL of a solution containing 0.100 M NaOH. Calculate the concentration of the resulting solution.
A. 0.050 M
B. 0.075 M
C. 0.100 M
D. 0.125 M

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