Viscosity is the property of the liquid by virtue of which it opposes the relative motion between its adjacent layers.

(A) The viscosity of an ideal fluid is zero.
(B) With the rise in temperature, the viscosity of liquids increase and that of gases decrease.
(C) The viscosity of gases is much less than that of liquids.
(D) Viscosity of liquid generally increase with increase in pressure.

Choose the correct answer from the options given below:

(A), (C) and (D) only

The correct answer is Option (3) → (A), (C) and (D) only

(A) The viscosity of an ideal fluid is zero: True. An ideal fluid is a theoretical concept defined as being both incompressible and non-viscous (having no internal friction). Therefore, its viscosity is zero.

(B) With the rise in temperature, the viscosity of liquids increase and that of gases decrease: False. * In liquids, viscosity is primarily due to cohesive forces between molecules. As temperature rises, these forces weaken, and the viscosity decreases.

• In gases, viscosity is due to the exchange of momentum between layers. As temperature rises, molecular motion increases, leading to more frequent collisions and momentum transfer, which increases the viscosity.

(C) The viscosity of gases is much less than that of liquids: True. Liquids have much stronger intermolecular (cohesive) forces compared to gases, making them significantly more resistant to flow.

(D) Viscosity of liquid generally increase with increase in pressure: True. For most liquids, as pressure increases, the molecules are forced closer together, increasing the cohesive forces and internal friction, thereby increasing the viscosity (though this effect is usually only significant at very high pressures).