PV = nRT

Where:

* P = Pressure (in atmospheres)

* V = Volume (in liters)

* n = Number of moles

* R = Ideal gas constant (0.0821 L·atm/mol·K)

* T = Temperature (in Kelvin)

1. Rearrange the equation to solve for V:

V = (nRT) / P

2. Plug in the given values:

V = (0.323 mol * 0.0821 L·atm/mol·K * 265 K) / 0.900 atm

3. Calculate the volume:

V ≈ 8.02 L

Therefore, the 0.323 mol sample of gas will occupy approximately 8.02 liters at 265K and 0.900 atm.