POST UTME REDEEMERS UNIVERSITY 2025 Chemistry | Objective

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Question 1
The s\tandard enthalpy of formation of CO_2(g) is -393.5 kJ/mol. The s\tandard enthalpy of formation of H_2O(l) is -285.8 kJ/mol. Calculate the s\tandard enthalpy of formation of CH_4(g).
A. -74.8 kJ/mol
B. -74.5 kJ/mol
C. -74.2 kJ/mol
D. -74.9 kJ/mol
Question 2
A solution of 0.1 M NaCl is prepared by dissolving 6.0 g of NaCl in 100 mL of water. What is the concentration of the solution in g/L?
A. 0.6 g/L
B. 1.2 g/L
C. 1.8 g/L
D. 2.4 g/L
Question 3
A 0.1 M solution of NaCl is prepared by dissolving 2.5 g of NaCl in 100 mL of water. What is the concentration of the solution in mol/L?
A. 0.043 M
B. 0.0435 M
C. 0.044 M
D. 0.0445 M
Question 4
Determine the pH of a 0.1 M solution of HCl at 25°C, given that the dissociation cons\tant of HCl is 10^\( -7 \) and the temperature dep\endence of the dissociation cons\tant is given by the equation: \log(K) = -0.5\( 1/T - 1/298.15 \) + 6.5.
A. 2
B. 3
C. 4
D. 5
Question 5
The pH of a solution is a measure of its acidity or basicity. What is the pH of a solution that has a hydrogen ion concentration of 1.0 x 10^-5 M?
A. 5.0
B. 6.0
C. 7.0
D. 8.0
Question 6
The element sulfur (S) exists in several allotropes, including rhombic sulfur and monoclinic sulfur. Which allotrope has a higher melting point?
A. Monoclinic sulfur
B. Rhombic sulfur
C. Both have the same melting point
D. Dep\ends on the temperature
Question 7
The reaction 2NO(g) + O2(g) → 2NO2(g) is an example of a ______ reaction.
A. combustion
B. synthesis
C. decomposition
D. redox
Question 8
The atomic radius of an element in a given period decreases as the atomic number increases. Which of the following elements has the largest atomic radius in period 3?
A. Phosphorus
B. Sulfur
C. Chlorine
D. Argon
Question 9
A solution of 0.1 M HCl is titrated with 0.1 M NaOH. If 20 mL of the HCl solution is required to reach the equivalence point, what is the pH of the solution at the equivalence point?
A. 7
B. 8
C. 9
D. 10
Question 10
The reaction of sodium hydroxide with acetic acid is an example of a reaction that exhibits which type of equilibrium?
A. Homogeneous equilibrium
B. Heterogeneous equilibrium
C. Chemical equilibrium
D. Physical equilibrium
Question 11
A sample of a hydrocarbon has a molecular formula of C4H10. What is the name of this hydrocarbon?
A. Bu\tane
B. Isobu\tane
C. n-Bu\tane
D. Isobutene
Question 12
A 2.5 L flask contains 0.5 mol of CO2 at 25°C. What is the partial pressure of CO2 in the flask?
A. 0.5 atm
B. 0.75 atm
C. 1 atm
D. 1.5 atm
Question 13
The reaction of hydrogen gas with oxygen gas is an example of a reaction that exhibits which type of periodicity?
A. Periodicity of atomic radius
B. Periodicity of electronegativity
C. Periodicity of ionization energy
D. Periodicity of electron affinity
Question 14
The reaction of acetic acid with sodium hydroxide is a classic example of a neutralization reaction. Write the balanced chemical equation for this reaction.
A. CH3COOH + NaOH → CH3COONa + H2O
B. CH3COOH + NaOH → CH3COONa + H2O2
C. CH3COOH + NaOH → CH3COONa + H2O3
D. CH3COOH + NaOH → CH3COONa + H2O4
Question 15
A solution contains 0.100 M sodium chloride (NaCl) and 0.0500 M calcium chloride (CaCl2). What is the total concentration of chloride ions \( Cl- \) in the solution?
A. 0.125 M
B. 0.150 M
C. 0.175 M
D. 0.200 M

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