Based on the given figure, the number of correct statement/s is/are ____
A. Surface tension is the outcome of equal attractive and repulsion forces acting on the liquid molecule in bulk. B. Surface tension is due to uneven forces acting on the molecules present on the surface. C. The molecule in the bulk can never come to the liquid surface. D. The molecules on the surface are responsible for vapour pressure if the system is a closed system.
Answer: 2
Solution
Surface tension originates in the molecules at the liquid surface, which, unlike those in the bulk, are pulled only inward and sideways and so feel a net unbalanced inward force; the claim that it comes from balanced forces on a bulk molecule is therefore wrong, while crediting it to the uneven forces on surface molecules is right. Molecules exchange freely between the bulk and the surface, so the statement that a bulk molecule can never reach the surface is wrong. In a closed vessel the surface molecules that gain enough energy escape above the liquid and set up the vapour pressure, so that statement is correct. The number of correct statements is two.
JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Integer answer
