AIIMS 2018 Physics Effects of Temperature MCQ Question
Assertion: Surface tension decreases with increase in temperature.
Reason: On increasing temperature kinetic energy increases and intermolecular forces decreases.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
As temperature increases, the kinetic energy of the molecules in a liquid, such as H₂O, rises, causing them to move more vigorously. This increased molecular motion weakens the intermolecular forces (e.g., hydrogen bonding in water), leading to a decrease in surface tension. Option B is incorrect because surface tension universally decreases with temperature for most liquids, while options C and D are misleading; although some exceptions exist, the general trend holds true across common liquids.
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