Question

A soap bubble assumes a spherical surface. Which of the following statement is wrong
A. The soap film consists of two surface layers of molecules back to back
B. The bubble encloses air inside it
C. The pressure of the air inside the bubble is less than the atmospheric pressure; that is why the atmospheric pressure has compressed it equally from all sides to give it a spherical shape.
D. Because of the elastic property of the fim, it will tend to shrink to as small a surface area as possible for the volume it has enclosed.

Answer 1

Hint: We know a soap bubble has two layers of molecules and it has a thin film of water which is surrounded by air. As we go deep into the water pressure goes on increasing. So the smaller the bubble, the greater the pressure exists in the bubble.

Complete step by step solution:
We answered the question by using the options. The soap film consists of two surface layers of molecules back to back. As we are talking about the air-liquid interfaces. The bubble soap consists of a thin layer of liquid. It has some finite thickness. The outermost layer of the soap is touching the air outside the bubble. That we called it the one surface. The innermost layer of the soap is touching the air inside the bubble. That is what we call the second surface.

A soap bubble consists of an especially thin film of soapy water that surrounds air that forms a hollow sphere with a shining surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. We know water exists at the top of the bubble. As you go deep in the water, pressure also increases.Then at whatever be the depth of the bubble, there is an increase going inside the bubble from outside. That's why the pressure inside the bubble is greater than atmospheric pressure. Smaller is the bubble, greater is the pressure inside.

A soap bubble's layer consists of various layers of molecules. An increase in the surface area causes the surface energy to also increase. This allows more and more molecules from the inner liquid layers of the bubble to attain potential energy. Hence, the surface area increases. As the surface area decreases it will naturally tend to shrink the bubble. Thus we see that Option (C) given in the question is incorrect.

Thus, option C is correct.

Note: In a soap bubble, remember that pressure inside the bubble must be greater than the pressure outside to remain stable. If the pressure outside the bubble gey greater then the bubble will collapse.