Question

An air bubble in a water tank rises from the bottom to the top. Which of the following statement(s) is/are true?

• A. Bubble rises upwards because pressure at the bottom is less than that at the top
• B. Bubble rises upwards because pressure at the bottom is greater than that at the top
• C. As the bubble rises, its size increases
• D. As the bubble rises, its size decreases

Answer 1

Answer: (B), (C)

As the bubble rises, its size increases

Option A: incorrect, because pressure increase as we go down in eater tank, it can also be visualised by hydrostatics law i.e. $\frac{dp}{dz}=\rho h$
Option B: correct, because the pressure at the bottom is greater
Option C: Correct, according to the ideal gas equation,
$PV=nRT$
$p\propto \frac{1}{V}$
As bubble rise pressure will decrease to the volume will increase. ($nRT$ is treated as constant ).
Option D: incorrect, as option c is correct it will be incorrect

​​​​​​​For more detailed solution watch the next video.