POST UTME UNN 2019 Chemistry | Objective

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Question 1
The s\tandard electrode potential of the couple Zn2+/Zn is -0.76 V. What is the s\tandard electrode potential of the couple Cu2+/Cu?
A. -0.34 V
B. -0.44 V
C. -0.54 V
D. -0.64 V
Question 2
A 2.50 g sample of a non-metallic oxide of nitrogen is decomposed by heating with graphite. The volume of nitrogen gas produced at 25°C and 1 atm is 2.50 L. Calculate the molar mass of the oxide.
A. 60 g/mol
B. 80 g/mol
C. 100 g/mol
D. 120 g/mol
Question 3
A solution of sodium hydroxide is added to a solution of acetic acid. The reaction is as follows: CH3COOH + NaOH → CH3COONa + H2O. If 25.0 mL of 0.100 M acetic acid is added to 50.0 mL of 0.100 M sodium hydroxide, what is the concentration of the resulting solution?
A. 0.0500 M
B. 0.100 M
C. 0.150 M
D. 0.200 M
Question 4
A 25 mL sample of 0.1 M HCl is titrated with 0.1 M NaOH. Calculate the number of moles of NaOH that have reacted after 15 mL of NaOH has been added.
A. 0.0025
B. 0.0050
C. 0.0075
D. 0.0100
Question 5
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. If the initial pH of the HCl solution is 1.00, what is the pH of the solution after the addition of 25.0 mL of NaOH?
A. 2.00
B. 3.00
C. 4.00
D. 5.00
Question 6
A reaction is represented by the equation: \( A \rightarrow 2B + C \). If the rate cons\tant for the reaction is 0.0500 s\( ^{-1} \) and the initial concentration of A is 0.100 M, what is the concentration of B after 10.0 s?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 7
Determine the oxidation state of nitrogen in the compound NO2.
A. +1
B. +2
C. +3
D. +4
Question 8
The reaction between HCl and NaOH is represented by the equation: HCl + NaOH → NaCl + H2O. If 50 mL of 0.1 M HCl is mixed with 50 mL of 0.1 M NaOH, what is the concentration of the resulting solution?
A. 0.05 M
B. 0.10 M
C. 0.15 M
D. 0.20 M
Question 9
A 1.0 M solution of HCl is prepared by dissolving 36.5 g of HCl in water to make 1.0 L of solution. What is the pH of the solution?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
Question 10
A 1.00 L sample of a gas at 25°C and 1.00 atm is collected over water at 25°C. What is the partial pressure of the gas?
A. 0.950 atm
B. 0.975 atm
C. 1.00 atm
D. 1.05 atm
Question 11
A 2.5 M solution of hydrochloric acid (HCl) is mixed with a 1.0 M solution of sodium hydroxide (NaOH). If the reaction is complete, what is the concentration of the resulting solution?
A. 1.75 M
B. 2.25 M
C. 2.5 M
D. 3.0 M
Question 12
The rate of reaction between hydrogen peroxide and potassium iodide is given by the equation: rate = k[HI]^2[H2O2]. If the rate of reaction is 0.025 M/s when [HI] = 0.1 M and [H2O2] = 0.05 M, calculate the value of k.
A. 0.05 M^-1 s^-1
B. 0.1 M^-1 s^-1
C. 0.2 M^-1 s^-1
D. 0.5 M^-1 s^-1
Question 13
A 2.0 L sample of a gas (G) is collected over water at a temperature of 25°C and a pressure of 1.0 atm. If the vapor pressure of water at 25°C is 0.031 atm, what is the partial pressure \( P_G \) of the gas?
A. 0.969 atm
B. 0.970 atm
C. 0.971 atm
D. 0.972 atm
Question 14
A reaction is represented by the equation: \( 2A + B \rightarrow 2C + D \). If the rate cons\tant for the reaction is 0.0500 s\( ^{-1} \) and the initial concentrations of A and B are 0.100 M and 0.0500 M, respectively, what is the concentration of A after 10.0 s?
A. 0.0500 M
B. 0.0750 M
C. 0.100 M
D. 0.125 M
Question 15
The reaction of an alkene with bromine in the presence of light produces a dibromoalkane. Write the equation for the reaction of 2-methylpropene with bromine.
A. (CH3)2C=CH2 + Br2 → (CH3)2CBrCH2Br
B. (CH3)2C=CH2 + Br2 → (CH3)2CBrCHBr
C. (CH3)2C=CH2 + Br2 → (CH3)2CBr2
D. (CH3)2C=CH2 + Br2 → (CH3)2CBrCH3

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