34. PV = n R T
calculate n number of moles. in one mole of sodium N = avogadro number of atoms are present.
35. from PV = n R T we get the number of moles of gaseous mixture..
We write the reactions of Ethane and Ethene with O2.. we know the mass of carbon and hydrogen in the mixture ..from H2, we know the number of moles of ethane and ethene..
now we calculate the proportion in the mixture.
36. from P V and T we find number of moles of water in the steam.
from that find mass of water. that was contained in magnesium sulphate.
so we subtract that from 54.2 gms.. so we get mass of magnesium sulphate dry...
now find proportion of moles of MG SO4 : moles of water... then we have x.
37. let us take length of alveoli = L cm
air volume = Pi R^2 L cc.
P , V, T of air known. So number of moles are calculated.
oxygen volume in alveoli = 14 % of air volume
perhaps we do take 14% of moles of air as moles of O2...
then we find number of molecules -- use avogadro number.