Consider 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 Reynold's number.
E. In a steady flow two stream lines never intersect.
Choose the correct answer from the options given below:
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 Reynold's number.
E. In a steady flow two stream lines never intersect.
Choose the correct answer from the options given below:
- (A)A, D, E only
- (B)C, D, E only✓ Correct
- (C)B, C, D only
- (D)A, B, C only
Answer: (B)
Solution
Checking each statement:
A. Surface tension arises because molecules at the surface have extra potential energy compared to those in the interior, not the other way round — false as stated.
B. The viscosity of a liquid decreases as temperature rises, since the intermolecular cohesive forces responsible for its viscosity weaken with heating — false.
C. The viscosity of a gas increases with temperature, since gas viscosity arises from momentum transfer between molecules in random motion, which intensifies as temperature rises — true.
D. The onset of turbulence is governed by the Reynolds number exceeding a critical value — true.
E. In steady (streamline) flow, two streamlines can never intersect, since a particle at a point of intersection could not have a single, well-defined velocity direction — true.
So statements C, D and E are correct.
A. Surface tension arises because molecules at the surface have extra potential energy compared to those in the interior, not the other way round — false as stated.
B. The viscosity of a liquid decreases as temperature rises, since the intermolecular cohesive forces responsible for its viscosity weaken with heating — false.
C. The viscosity of a gas increases with temperature, since gas viscosity arises from momentum transfer between molecules in random motion, which intensifies as temperature rises — true.
D. The onset of turbulence is governed by the Reynolds number exceeding a critical value — true.
E. In steady (streamline) flow, two streamlines can never intersect, since a particle at a point of intersection could not have a single, well-defined velocity direction — true.
So statements C, D and E are correct.
JEE Main · 2025 · 28 Jan 2025 · Shift 1 · Single correct option