Answer: 3 moles
Step-by-step explanation:
Using the ideal gas equation; PV = nRT
P= Pressure= 2.1 Atm V= Volume = 3.5L T= Temperature = 315K
n= no of moles
R= Gas constant = 0.08206 L .atm. mol-1 . K-1
Making 'n' the subject of the formular, we then have;
n = PV / RT
= 2.1 Atm x 3.5L / 0.08206 L .atm. mol-1 . K-1 x 315K
= 7.35 / 25.849
= 0.28 approx 3moles