Answer
$ 3 \times 10^{23} $ molecules
Work Step by Step
In order to solve this problem, we first must find how many moles there are using $PV= nRT. $
We simplify the equation and solve:
$ n = \frac{PV}{RT} \\ n = \frac{180,000Pa \times 8.5 \times 10^{-3} m^3}{(8.31 J/K) \times 350 K} \\ n = .53 \space mols$
Since there are $6.022 \times 10^{23}$ molecules in a mole, this means that there are $3 \times 10^{23}$ molecules.