OAT General Chemistry 4 — Questions and Answers
Question 1: Which of the following salts will produce a basic solution when dissolved in water?
- NH4Cl
- NaCl
- Na2CO3 (Correct answer)
- KNO3
Correct answer: Na2CO3
Na2CO3 is the salt of a strong base (NaOH) and weak acid (H2CO3), so its solution is basic due to hydrolysis of CO3²⁻.
Question 2: What is the hybridization of the carbon atom in CO2?
- sp3
- sp2
- sp (Correct answer)
- sp3d
Correct answer: sp
Carbon in CO2 forms two double bonds with no lone pairs, requiring sp hybridization with a linear geometry.
Question 3: The Ksp of AgCl is 1.8 × 10⁻¹⁰. What is the molar solubility of AgCl in pure water?
- 1.8 × 10⁻¹⁰ M
- 1.3 × 10⁻⁵ M (Correct answer)
- 3.6 × 10⁻¹⁰ M
- 9.0 × 10⁻⁶ M
Correct answer: 1.3 × 10⁻⁵ M
For AgCl → Ag⁺ + Cl⁻, Ksp = s² = 1.8×10⁻¹⁰, so s = √(1.8×10⁻¹⁰) ≈ 1.3×10⁻⁵ M.
Question 4: Which of the following colligative properties depends on the number of solute particles in solution?
- Color of the solution
- Viscosity of the solution
- Boiling point elevation (Correct answer)
- Density of the solution
Correct answer: Boiling point elevation
Boiling point elevation (ΔTb = Kb × m × i) is a colligative property that depends on solute particle concentration.
Question 5: Which of the following best describes a zero-order reaction?
- Rate doubles when concentration doubles
- Rate is independent of reactant concentration (Correct answer)
- Rate depends on the square of reactant concentration
- Rate decreases as concentration increases
Correct answer: Rate is independent of reactant concentration
In a zero-order reaction, the rate is constant and does not depend on the concentration of the reactant.
Question 6: Which intermolecular force is responsible for the relatively high surface tension of water?
- London dispersion forces
- Dipole-dipole interactions
- Hydrogen bonding (Correct answer)
- Ion-dipole interactions
Correct answer: Hydrogen bonding
Hydrogen bonding between water molecules creates strong cohesive forces, resulting in high surface tension.
Question 7: What happens to the equilibrium constant K when the temperature of an exothermic reaction is increased?
- K increases
- K decreases (Correct answer)
- K remains unchanged
- K becomes zero
Correct answer: K decreases
For an exothermic reaction, increasing temperature shifts equilibrium toward reactants, decreasing K.
OAT General Chemistry 4
Which of the following salts will produce a basic solution when dissolved in water?