Question

the ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1:4. The ratio of number of molecules is ???

Answer 1

mass of oxygen/mass of nitrogen=1/4. Mole=weight / atomic weightMole of oxygen be 1x/32 and mole of nitrogen be 4x/32=x/7Mole=no.of molecules /NATherefore,mole of oxygen(x/32)=No.of molecules /NA Therefore no.of molecules =NA/32.....1Mole of nitrogen (x/7)=No.of molecules /NATherefore NA/7=no.of molecules .......2From1 and 2NA/32=NA/7Therefore 7NA=32NA.....(cross multiplying) i.e.7:32