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# Test: Surface Tension

## 10 Questions MCQ Test Physics For JEE | Test: Surface Tension

Description
This mock test of Test: Surface Tension for JEE helps you for every JEE entrance exam. This contains 10 Multiple Choice Questions for JEE Test: Surface Tension (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Surface Tension quiz give you a good mix of easy questions and tough questions. JEE students definitely take this Test: Surface Tension exercise for a better result in the exam. You can find other Test: Surface Tension extra questions, long questions & short questions for JEE on EduRev as well by searching above.
QUESTION: 1

### The angle of contact for the liquid which wets the walls of the vessel is

Solution:

When liquid molecules are attracted strongly to themselves and weakly to those of solids, it costs lots of energy to create liquid-solid surface and liquid then does not wet the solid.
For Example: Mercury molecules (which make an obtuse angle with glass) have a strong force of attraction between themselves and a weak force of attraction toward solids. Hence, they tend to form drops.
On the other hand, water molecules make acute angles with glass. They have a weak force of attraction between themselves and a strong force of attraction toward solids. Hence, they tend to spread out.

QUESTION: 2

### The surface tension of a soap solution is 0.05 Nm-1. How much work is done to produce a soap bubble of radius 0.03 m?

Solution:

Work done=total surface x Surface tension
=2x4πr2
=2x4x3.14(0.03)2x 0.05
=1.1x10-3J

QUESTION: 3

### The property by virtue of which the free surface of a liquid at rest behaves like an elastic stretched membrane tending to contract so as to occupy minimum surface area is known as

Solution:

The property by virtue of which the free surface of a liquid at rest behaves like an elastic stretched membrane tending to contract so as to occupy minimum surface area is known as surface tension. By the definition of surface tension.

QUESTION: 4

The force required to take away a flat plate of radius 4 cm from the surface of water is (surface tension of water = 70 dyne/cm)

Solution:

Force due to surface tension acts all along the circumference of the circular plate. Therefore, force required to take away of plate is,
F = T x 2πr = 70 x 2 x 3.14 x 4 = 1758.4 dyne/cm

QUESTION: 5

The liquid that does not wet the solid surface has an ______ angle of contact.

Solution:

When liquid molecules are attracted strongly to themselves and weakly to those of solids, it costs lots of energy to create liquid-solid surface and liquid then does not wet the solid.

For Example: Mercury molecules (which make an obtuse angle with glass) have a strong force of attraction between themselves and a weak force of attraction toward solids. Hence, they tend to form drops.
On the other hand, water molecules make acute angles with glass. They have a weak force of attraction between themselves and a strong force of attraction toward solids. Hence, they tend to spread out.

QUESTION: 6

When wetting agents like soap or dyes are added to water, the angle of contact becomes

Solution:

When wetting agents like soap or dyes are added to water, the angle of contact becomes small. This happens so that the particles penetrate well and become effective.

QUESTION: 7

When the salt is added to water, the surface tension of liquid mixture will

Solution:

NaCl salts cause an increase of the surface tension and the residence time of interfacial water molecules.

QUESTION: 8

The pressure inside a bubble of radius R and surface tension S is

Solution:

From the concept of surface tension; pressure inside the bubble = 4S/R.

QUESTION: 9

Which of the following expression is true for surface tension?

Solution:

The force acting on this line is proportional to the length of this line. If l is the length of imaginary line and F the total force on either side of the line then,
F∝l
⇒ F=Sl
Or, surface tension, S=force/length
From this expression, Surface tension can be defined as the force acting per unit length of an imaginary line drawn on the liquid surface, the direction of force being perpendicular to this line and tangential to the liquid surface.it is denoted by S and it is a scalar quantity.

QUESTION: 10

Angle of contact of water proofing agent are generally

Solution:

When a liquid surface meets a solid surface the angle (φ) between the two surfaces is important. In fact a surface will be wetted by water if the angle of contact is less than 90o, and so waterproofing is designed to produce an angle of contact that is greater than 90o.