Tutoring with Mukesh Saha

Answer

atomic mass og oxygen=16 gm

compound contains 3.2% oxygen by mass

therefore, mass of 3.2% compound=16gm

mass of compound=16*100/3.2=500gm

Answer

atomic wieght of nitrogen=14 gm

194 gm of caffine contains 28.9 % nitrogen=28.9*194/100=56gm

therefore number of nitrogen atoms=56/14=4