A gaseous mixture containing 0.35 g of N2 and 5600ml of O2 at STP is kept in a 5litre flask at 300K. The total pressure of the gaseous mixture is?

Moles of O2 = 5600/ 22400 = 0.25 mole

Moles of N2 = 0.35/ 28= 0.0125 mole

Temperature = 300 K, Volume = 5 L
R = 0.0821 Latm/Kmol

Partial pressure of Oxygen,
pO = n ×RT/V = 0.25 ×0.0821 × 300/ 5 = 1.231 atm

Partial pressure of Nitrogen pN = n ×RT/V = 0.0125 × 0.0821 × 300/ 5 = 0.0615 atm

Hence total pressure P = pO + pN = 1.231 + 0.0615 =1.298 atm