A sealed cylinder with a piston is filled with an ideal gas (See Start). The piston is slowly moved
until it is in the 'end' position. Which of the following stateents describes the change that
occurs? Start o End 10. O If the temperature remains constant, the pressure increases. O The
number of moles of the gas decreases The volume remains constant but the temperature
decreases. O The density of the gas (g/mL) in the cylinder decreases. O The pressure and
temperature in the cylinder both decrease.
Solution
Here volume is decreasing:
option 1 is correct.
since T is constant,
Pi*Vi = Pf*Vf
since Vf < Vi, we have: Pf > Pi
option 2 is wrong.
The number of mol of gas is not changing since no gas is allowed to escape
option 3 is wrong.
here volume is decreasing
option 4 is wrong.
density = mass / volume
since mass is same and volume is decreasing, density should increase
option 5 is wrong.
It can be said with accuracy
Answer: option 1