Help me in the 10 the number. Clue- helium and hydrogen make up the first of these

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.

Nitrogen dioxide decomposes according to the reaction 2 no2(g) ⇌ 2 no(g) + o2(g) where kp = 4.48 × 10−13 at a certain temperature. if 0.70 atm of no2 is added to a container and allowed to come to equilibrium, what are the equilibrium partial pressures of no(g) and o2(g)