NEET 2022 · PhysicsPrevious Year Question
The volume occupied by the molecules contained in 4.5 kg of water at STP, if the intermolecular forces vanish away, is:
Answer: (D) 5.6 m³. Correct Answer (D): 5.6 m³ If the intermolecular forces vanish, the water molecules behave as an ideal gas, so we apply PV = nRT at STP.
- A.5.6 × 10⁶ m³
- B.5.6 × 10³ m³
- C.5.6 × 10⁻³ m³
- D.5.6 m³✓
Correct Answer
(D) 5.6 m³
Solution & Explanation
Correct Answer (D): 5.6 m³ If the intermolecular forces vanish, the water molecules behave as an ideal gas, so we apply PV = nRT at STP. The amount of substance is n = mass/molar mass = 4500 g / 18 g mol⁻¹ = 250 mol. At STP (P = 1 × 10⁵ Pa, T ≈ 273 K) one mole occupies about 22.4 × 10⁻³ m³, so 250 mol occupies ≈ 5.6 m³.
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