Moles of the unknown gas in the flask : 0.216
Further explanation
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
V=5 L
P = 1.05 atm
T = 296 K
[tex]\tt n=\dfrac{PV}{RT}\\\\n=\dfrac{1.05\times 5}{0.082\times 296}\\\\n=0.216[/tex]
