You Wish to Measure the Extent of Reaction by Monitoring $\circ$

You wish to measure the extent of reaction by monitoring pressure changes.Suppose 1.000 atm of tungsten hexafluoride gas at 400.00 ^$\circ$ C in a 20.0 L deposition chamber partially decomposes to form tungsten metal and fluorine gas.The products of the reaction at this point are cooled to 25.00 ^$\circ$ C.The resulting pressure,which is due to the sum of the pressures of F₂ and leftover WF₆,is 1.028 atm.What is the pressure due to the unreacted WF₆? WF₆(g) $\to$ W(s) + 3 F₂(g)

A) 0.3395 atm
B) 0.6605 atm
C) 0.9830 atm
D) 0.1230 atm
E) 0.1504 atm