1996 General Studies, all questions
UPSC Prelims 1996 · General Studies
Question 115: Science and Technology
When an air bubble at the bottom of a lake rises to the top, it will
aincrease in size
bdecrease in size
cmaintain its size
dflatten into a disk-like shape
AnswerThe answer is (a).
As a bubble rises from the bottom of a lake, the pressure on it falls, because water pressure decreases with decreasing depth. By Boyle's law (pressure x volume stays constant at constant temperature), its volume increases, so the bubble grows as it rises. Remember: lower pressure - larger volume.
Why each option is right or wrong
- (a) Right: the pressure falls as it rises, so it expands.
- (b) Pressure falls as it rises, so it cannot shrink.
- (c) Volume changes with pressure (Boyle's law).
- (d) Surface tension keeps a bubble roughly spherical.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1996, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.