In a closed cylinder there are 60 g Ne and 64 g O2. If pressure of mixture of gases in cylinder is 30 bar, then partial pressure of O2 in this cylinder will be (in bar).
As partial pressure ∝ number of moles
where μO2=6432=2 and μNe=6020=3
⇒PO230 bar=22+3⇒PO2=12 bar