If a gas is initially at 5.50 atm, 121 l, 293 k, then it changes to 5.15 atm and 298 k, what is the new volume?

  The new volume  of the gas  is  131.43   liters
    
                    calculation

This is calculated  by use of combined  gas law equation

that is p1V1/T1 = P2V2/T2

P1 = 5.50  atm
V1= 121 L
T1= 293  k
P2=   5.15  atm
T2 = 298 K
V2 =?

by  making V2 the   subject of the  formula

V2=  T2 P1V1/ P2T1

V2  is therefore =  (298 k x 5.50  atm   x121 L)/  (  5.15  atm  x 293 k)  = 131.43  L

Your awser would be a acetone

Higher temperature = molecules move around faster. and vice versa.