The diagram above illustrates a beaker of water being heated. It is observed that as the bubbles rise they get bigger in size.The reason for this observation is?

A. water pressure on the bubbles decreases
B. density of water increases with rise in temperature
C. volume of water increases with rise in temperature
D. atmospheric pressure on the bubbles decreases

Correct Answer: Option A

A. water pressure on the bubbles decreases

Explanation

When a bubble is deep under water, it has both atmospheric pressure and water pressure (giving it depth), acting on it but as it rises, the water pressure decreases. At this point, the basic pressure acting on the bubble is the atmospheric pressure. Recall that pressure is inversely proportional to volume (Boyles’ law), hence, the less the pressure, the more the volume.