Surface Energy and Surface Tension (Angle of Contact, Excess of Pressure Across a Curved Surface, Application of Surface Tension - Drops, Bubbles, and Capillary Rise...)
Surface Energy and Surface Tension (Angle of Contact, Excess of Pressure Across a Curved Surface, Application of Surface Tension - Drops, Bubbles, and Capillary Rise...) MCQ Questions
1.
Surface tension is defined as:
A.
Pressure difference across a curved surface
B.
Energy per unit volume
C.
Force per unit volume of liquid
D.
Force per unit length acting in the plane of the liquid surface
ANSWER :
D. Force per unit length acting in the plane of the liquid surface
2.
The SI unit of surface tension is:
ANSWER :
B. N m⁻¹ (or J m⁻²)
3.
Surface energy arises because molecules at the surface of a liquid:
A.
Have zero kinetic energy
B.
Are surrounded only on the lower half — have fewer neighbours, so have higher potential energy than interior molecules
C.
Experience attraction from all surrounding molecules equally
D.
Have greater kinetic energy than interior molecules
ANSWER :
B. Are surrounded only on the lower half — have fewer neighbours, so have higher potential energy than interior molecules
4.
In NCERT's stretched film experiment, a bar of length l is moved by distance d on a liquid film. The work done against the surface tension force is:
A.
W = 2 × S × l × d (factor 2 for two surfaces of film)
ANSWER :
A. W = 2 × S × l × d (factor 2 for two surfaces of film)
5.
Surface tension of a liquid generally ___ with increasing temperature:
A.
First increases then decreases
6.
From NCERT Table 9.3, the surface tension of water at 20°C is approximately:
