Which of the following is the correct expression for the equilibrium constant (Kc) for the reaction: N₂(g) + 3H₂(g) ⇌ 2NH₃(g)?
Answer: A
The equilibrium constant expression follows the law of mass action where Kc = [products]^coefficients/[reactants]^coefficients. For this reaction, Kc = [NH₃]²/([N₂][H₂]³).
Q.2Easy
What is the pH of a 0.01 M HCl solution?
Answer: B
HCl is a strong acid and completely dissociates. [H⁺] = 0.01 M = 10⁻² M. Therefore, pH = -log[H⁺] = -log(10⁻²) = 2.
Q.3Easy
The rate constant of a first-order reaction is 0.693 s⁻¹. What is the half-life of this reaction?
Answer: B
For a first-order reaction, t₁/₂ = 0.693/k = 0.0693.693 = 1 s. This uses the relationship ln(2) ≈ 0.693.
Q.4Easy
For the reaction: 2A + B → C, if the rate law is Rate = k[A]²[B], what is the overall order of the reaction?
Answer: C
The overall order of a reaction is the sum of all exponents in the rate law. Here, order = 2 + 1 = 3.
Q.5Easy
What is the relationship between ΔG, ΔH, and ΔS?
Answer: A
The Gibbs free energy equation is ΔG = ΔH - TΔS, where T is temperature in Kelvin. This is fundamental to predicting spontaneity.
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Q.6Easy
At 298 K, the solubility product of AgCl is 1.8 × 10⁻¹⁰. What is the solubility of AgCl in mol/L?
Answer: A
For AgCl, Ksp = [Ag⁺][Cl⁻] = s². So s = √(1.8 × 10⁻¹⁰) = 1.34 × 10⁻⁵ mol/L
Q.7Easy
Which of the following exhibits the highest lattice energy?
Answer: B
MgO has the smallest ionic radii and highest charge density among options, leading to maximum lattice energy (~3850 kJ/mol)
Q.8Easy
For the reaction 2H₂ + O₂ → 2H₂O, ΔH = -572 kJ/mol. How much heat is released when 4 moles of H₂ react?
Answer: C
Given reaction releases 572 kJ for 2 moles of H₂. For 4 moles of H₂, heat released = (2572) × 4 = 1144 kJ
Q.9Easy
The osmotic pressure of a solution at 27°C containing 0.1 mol of solute in 1 L is approximately:
Answer: A
π = nRT/V = (0.1 × 0.0821 × 300)/1 = 2.463 atm
Q.10Easy
For a first-order reaction with half-life of 69.3 minutes, the rate constant k is:
Answer: A
For first-order reaction: t₁/₂ = 0.693/k, so k = 0.69693.3 = 1.0 × 10⁻³ min⁻¹
Q.11Easy
In electrochemistry, the reduction potential of Cu²⁺/Cu is +0.34 V and Zn²⁺/Zn is -0.76 V at 25°C. What is E°cell for Zn-Cu cell?