The Correct Answer Is (2) C, D, E Only.
Explanation
Statement A:
Surface tension arises due to extra energy of the molecules at the interior as compared to the molecules at the surface, of a liquid.
False. Surface tension arises because molecules at the surface of a liquid experience an imbalance of forces (they are pulled inward by molecules in the bulk of the liquid but have no neighboring molecules above them). This results in the surface molecules having higher potential energy compared to molecules in the interior, not extra energy. The surface tension is a consequence of this energy difference.
Statement B:
As the temperature of liquid rises, the coefficient of viscosity increases.
False. For liquids, as temperature increases, the kinetic energy of the molecules increases, reducing the intermolecular forces. This causes the viscosity of the liquid to decrease, not increase.
Statement C:
As the temperature of gas increases, the coefficient of viscosity increases.
True. For gases, viscosity increases with temperature. This is because gas molecules move faster at higher temperatures, leading to more frequent collisions and greater momentum transfer between layers of the gas, which increases viscosity.
Statement D:
The onset of turbulence is determined by Reynold’s number.
True. The Reynolds number (Re) is a dimensionless quantity used to predict the transition from laminar to turbulent flow. When Re exceeds a critical value (typically around 2000–4000 for pipe flow), the flow becomes turbulent.
Statement E:
In a steady flow, two streamlines never intersect.
True. Streamlines represent the path of fluid particles in steady flow. If two streamlines were to intersect, it would imply that a fluid particle could have two different velocities at the same point, which is physically impossible in steady flow.
