Asked in ETEA MDCAT 2006 2006Moderate

The lowest vapor pressure is exerted by:

Correct answer: C. Mercury

  • A. Water
  • B. Kerosene oil
  • C. Mercury
  • D. rectified spirit

Explanation

Vapor pressure is determined by the strength of intermolecular forces, with weaker forces leading to higher vapor pressure. In this case, mercury has the lowest vapor pressure because it has the strongest intermolecular forces compared to water, kerosene oil, and rectified spirit. This is why mercury is the correct answer. Water has stronger intermolecular forces than kerosene oil, rectified spirit, and mercury, resulting in higher vapor pressure. Kerosene oil has weaker intermolecular forces than water and mercury, leading to higher vapor pressure. Rectified spirit falls between kerosene oil and water in terms of intermolecular forces, resulting in higher vapor pressure than mercury.

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About Evaporation, Boiling Point and Vapour Pressure

Evaporation is the escape of higher-energy molecules from a liquid surface, while vapour pressure is the pressure exerted by vapour in equilibrium with that liquid. The topic distinguishes evaporation from boiling and relates both to temperature, intermolecular forces, surface area, atmospheric pressure and the boiling point.

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