Explanation:
a) [tex]n = \dfrac{PV}{RT} = \dfrac{(1.8×10^7\:\text{Pa})(3\:\text{L})}{(8310\:\text{L•Pa/mol•K})(300\:\text{K})}[/tex]
[tex]\:\:\:\:\:\:\:= 21.7\:\text{mol}[/tex]
b) [tex]P = \dfrac{nRT}{V}[/tex]
[tex]\:\:\:\:\:\:\:\:\:= \dfrac{(50\:\text{mol})(8310\:\text{L•Pa/mol•K})(300\:K)}{(3\:L)}[/tex]
[tex]\:\:\:\:\:\:\:\:\:=4.2×10^7\:\text{Pa}[/tex]
