Answer:
There are 2, 01 moles of helium in the container
Explanation:
We use the formula PV=nRT. We convert of pressure the unit kPa into atm:
101,325 kPa---1 atm
245 kPa ----x= (245 kPa x 1 atm)/101,325 kPa=2,42 atm
PV= nRT ---> n=PV/RT
n= 2, 42 atm x 21, 5 L/ 0,082 l atm /K mol x315K
n=2, 012620871 mol