Question

The INCORRECT statement is

• A. A liquid incompressible and has free surface of its own
• B. A gas is compressible and occupy all the space available to it.
• C. Pressure in a fluid at rest is same at all points which are at same height
• D. The surface of water in a capillary is concave
• E. Surface tension is a force per unit area

Answer 1

Answer: (E)

Surface tension is a force per unit length, not force per unit area. The definition of surface tension is the force acting along the surface of a liquid, which tends to minimize the surface area. It is measured in units of force per unit length (N/m). The incorrect statement in the given options is (E), as surface tension is not defined as force per unit area.

The correct option is (E) : Surface tension is a force per unit area

Answer 2

Let's analyze each statement:  

1. A liquid is incompressible and has free surface of its own: ✔️ True. Liquids are nearly incompressible and form a free surface when not fully enclosed. 

2. A gas is compressible and occupies all the space available to it: ✔️ True. Gases expand to fill their containers and are highly compressible. 

3. Pressure in a fluid at rest is same at all points which are at same height: ✔️ True. This is a fundamental property of fluids in hydrostatic equilibrium. 

4. The surface of water in a capillary is concave: ✔️ True. Due to adhesion between water and glass being stronger than cohesion between water molecules. 

5. Surface tension is a force per unit area: ❌ Incorrect. Surface tension is actually force per unit length (N/m), not per unit area. 

Correct answer: Surface tension is a force per unit area