POST UTME LASU 2019 Chemistry | Objective

Practice these randomly selected questions to test your readiness.

Question 1
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 50 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 10^5 s^-1
B. 1.0 x 10^6 s^-1
C. 1.0 x 10^7 s^-1
D. 1.0 x 10^8 s^-1
Question 2
A metal M has a s\tandard electrode potential of +0.5 V. What is the s\tandard potential of the cell formed by depositing M at the cathode and oxidizing M at the anode?
A. -0.5 V
B. +0.5 V
C. +1 V
D. -1 V
Question 3
A diagram of a simple electrolytic cell is shown below. If the cell is operated at a cons\tant current of 2 A for 5 minutes, what is the mass of copper deposited at the cathode?
A. 0.12 g
B. 0.24 g
C. 0.36 g
D. 0.48 g
Question 4
A solution contains 0.1 M HCl. If 10 mL of this solution is added to 100 mL of 0.1 M NaOH, what is the pH of the resulting solution?
A. 1
B. 2
C. 3
D. 4
Question 5
A sample of a non-metallic oxide has a molar mass of 80 g/mol. If 5.0 g of the oxide is decomposed, what is the volume of oxygen gas produced at STP?
A. 2.0 L
B. 4.0 L
C. 6.0 L
D. 8.0 L
Question 6
A 2.0 M solution of a salt is prepared by mixing 10 mL of 1 M NaOH with 20 mL of 1 M HCl. What is the concentration of the resulting solution?
A. 0.5 M
B. 1.0 M
C. 2.0 M
D. 4.0 M
Question 7
The s\tandard enthalpy of formation of CO2 is -393.5 kJ/mol. What is the s\tandard enthalpy of combustion of 1 mole of CO?
A. -110.5 kJ/mol
B. -111.5 kJ/mol
C. -112.5 kJ/mol
D. -113.5 kJ/mol
Question 8
The electronegativity of an element in a compound is a measure of its ability to attract electrons towards itself. Which of the following elements has the highest electronegativity among the given options?
A. Fluorine (F)
B. Chlorine (Cl)
C. Bromine (Br)
D. Iodine (I)
Question 9
The reaction between sodium (Na) and chlorine (Cl2) to form sodium chloride (NaCl) is an example of a redox reaction. What is the oxidation state of sodium in NaCl?
A. +1
B. -1
C. 0
D. +2
Question 10
A metal alloy is made by mixing 30% Cu, 20% Zn, and 50% Sn. What is the percentage of Cu in the alloy?
A. 15%
B. 20%
C. 25%
D. 30%
Question 11
A solution of CuSO4 is electrolyzed u\sing a platinum electrode. What is the product at the anode?
A. O2
B. Cu
C. SO2
D. H2O
Question 12
A solution of HCl is electrolyzed u\sing a platinum electrode. What is the product at the cathode?
A. H2
B. Cl2
C. H2O
D. NaCl
Question 13
The rate cons\tant for a first-order reaction is 0.05 min^-1. What is the half-life of the reaction?
A. 10 min
B. 20 min
C. 30 min
D. 40 min
Question 14
A 0.5 M solution of sodium carbonate (Na2CO3) is titrated with a 1.0 M solution of hydrochloric acid (HCl). If 40 mL of the acid solution is required to reach the equivalence point, calculate the number of moles of sodium carbonate (Na2CO3) present in 50 mL of the solution.
A. 0.05
B. 0.10
C. 0.15
D. 0.20
Question 15
The reaction between potassium permanganate and oxalic acid is a classic example of a redox reaction. The balanced equation for this reaction is: \( 2KMnO_4 + 5H_2C_2O_4 + 3H_2SO_4 \rightarrow K_2SO_4 + 2MnSO_4 + 10CO_2 + 8H_2O \). What is the oxidation state of manganese in the product \( MnSO_4 \)?
A. 0
B. +2
C. -2
D. +4

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