Answer:
n = 0.6 mol
Step-by-step explanation:
I assume this is for the ideal gas law:
PV = nRT
P = 10 atm, V = 2 L, and T = 400 K
You need to choose a R value that has the same units. In this case:
R = 0.0821 L atm /K /mol
Plugging in and solving for n:
(10 atm) (2 L) = n (0.0821 L atm /K /mol) (400 K)
n = 0.61 mol
Rounding to one significant figure, n = 0.6 mol.