AAMC prac exam 8: question 28

[strive01]

I understood the graph and that temperature was decreasing with depth and so I thought that as the pressure decreases as the balloon rises, volume would increase and since when gasses expand, the temperature cools.. i thought A was appropriate.. perhaps what i dont understand is the work done on vs. work done by .. is that what made B the right answer?

if you could help me with this, id appreciate it

also, i wanted to know some opinions if exam 8 and 7 are harder than the real mcat.. that is what it says on the TPR website but is there any truth to that?

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[sepho]

You've misinterpreted the graph: temperature was INCREASING with depth. The graph is slightly misleading with time going backwards (in the graph). So as the pressure exerted on the balloon decreases on the way up, the gas will expand and decrease temperature. So B is correct. The work done by the gas to expand the balloon on the way up, caused energy to flow out of the balloon, and decrease temperature.

Hope this helps.