At 298 K, the vapor pressure of water is 23.8 mmHg. What is the mole fraction of water vapor in saturated air at this temperature?
Answer: A
Mole fraction = vapor pressure of water / total atmospheric pressure = 23.7608 = 0.0313
Q.22Easy
For the reaction: N₂O₄(g) ⇌ 2NO₂(g), ΔH = 58 kJ/mol. If pressure is increased at constant temperature, the equilibrium will:
Answer: B
Increasing pressure favors the side with fewer moles of gas. 1 mole N₂O₄ ⇌ 2 moles NO₂. Equilibrium shifts left.
Q.23Easy
Which electrochemical cell cannot be recharged?
Answer: B
Daniell cell is a primary cell (non-rechargeable). Others are secondary (rechargeable) cells.
Q.24Easy
At 273 K, 1 mole of an ideal gas occupies 22.4 L. What will be its volume at 546 K and same pressure?
Answer: B
Using Charles's Law: V₁/T₁ = V₂/T₂ → V₂ = V₁ × (T₂/T₁) = 22.4 × (273546) = 44.8 L
Q.25Easy
The rate constant for a first-order reaction is 0.693 min⁻¹. What is its half-life?
Answer: B
For first-order reaction: t₁/₂ = 0.693/k = 0.0693.693 = 1 min
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Q.26Easy
When 50 mL of 0.1 M HCl is mixed with 50 mL of 0.1 M NaOH, the resulting solution will have:
Answer: A
Equivalent moles of strong acid and strong base neutralize completely. The salt NaCl formed doesn't hydrolyze. pH = 7
Q.27Easy
Which of the following factors does NOT affect the position of chemical equilibrium?
Answer: C
A catalyst speeds up both forward and reverse reactions equally, so it does not change the position of equilibrium. It only helps the system reach equilibrium faster.
Q.28Easy
A solution has [H⁺] = 10⁻⁴ M at 25°C. What is the pH and pOH of this solution?
In a galvanic cell, which statement is always true?
Answer: D
In a galvanic cell, the anode is where oxidation occurs and is the negative electrode. Electrons flow from anode to cathode through the external circuit.
Q.30Easy
Which colligative property is independent of the nature of the solute?
Answer: D
All colligative properties (boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering) depend only on the number of solute particles, not their nature.
Q.31Easy
In the Nernst equation at 25°C, what is the value of (2.303RT/F)?
Answer: C
At 25°C (298 K), (2.303RT/F) = (2.303 × 8.314 × 298)/96485 ≈ 0.0592 V. This is commonly used in half-cell potential calculations.
