Question

Consider the following statements: 
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. 
B. As the temperature of liquid rises, the coefficient of viscosity increases. 
C. As the temperature of gas increases, the coefficient of viscosity increases. 
D. The onset of turbulence is determined by Reynolds number. 
E. In a steady flow, two streamlines never intersect.
Choose the correct answer from the options given below:

• A. A, B, C Only
• B. A, D, E Only
• C. B, C, D Only
• D. C, D, E Only

Hint:

When analyzing fluid dynamics, remember that Reynolds number is crucial for determining the nature of flow (laminar or turbulent).

Answer 1

The Correct Option is D

Analysis of each statement:

A. Surface tension arises due to extra energy of the molecules at the surface as compared to the molecules at the interior of a liquid.
Surface molecules experience a net inward force from molecules below, resulting in higher energy and thus surface tension. Statement A is incorrect.

B. As the temperature of a liquid rises, the coefficient of viscosity decreases.
Increased temperature weakens cohesive forces between liquid molecules, facilitating flow and decreasing viscosity. Statement B is incorrect.

C. As the temperature of a gas increases, the coefficient of viscosity increases.
In gases, viscosity is due to momentum transfer. Higher temperatures increase molecular speed and collision frequency, enhancing momentum transfer and thus viscosity. Statement C is correct.

D. The onset of turbulence is determined by the Reynolds number.
The Reynolds number quantifies flow regime; low values indicate laminar flow, high values indicate turbulent flow. Statement D is correct.

E. In a steady flow, two streamlines never intersect.
Streamlines indicate fluid flow direction. Intersection would imply a fluid particle has multiple velocities, which is impossible in steady flow. Statement E is correct.

Final Answer:
Correct statements are C, D, and E.

The final answer is $ \boxed{C, D \text{ and } E \text{ only}} $.