Given;
P= 684 mm Hg=684/760 atm
T=300 K
R=0.08 atm-L/mol-K
Molecular mass of nitrogen =28 g/mol
From, PV=nRT
Weight of Nitrogen in organic compound=PV×M.wtRT
=684×50×10−3×280.08×760×300=0.0525 g
% of N in organic comp. =Mass of N in organic compTotal mass of organic comp.(w)×100
⇒12.5=0.0525w×100
⇒w=0.42
So, 0.42×100=42