Volume of Argon = 59.972 L
In general, the gas equation can be written
[tex]\large {\boxed {\bold {PV = nRT}}}[/tex]
where
P = pressure, atm
V = volume, liter
n = number of moles
R = gas constant = 0.08206 L.atm / mol K
T = temperature, Kelvin
At STP(0 C, 1 atm), 1 mol gas= 22.4 L
so for 20 L
[tex]\tt \dfrac{20}{22.4}=0.893[/tex]
For Argon
P = 1 atm
T = 273 K x 3 =819 K (tripled)
n = 0.893 (the same number of moles)
R = 0.082 L/atm.mol K
[tex]\tt V=\dfrac{nRT}{P}=\dfrac{0.893\times 0.082\times 819}{1}=59.972~L[/tex]