KEAM 2019 Physics and Chemistry Paper

Given, methanol =20mL
Water =80mL
density of methanol =0.793kgL−1 or 0.793gmL−1
density of solution =0.964kgL−1 or 0.964gmL−1
As, density =‌

‌ mass ‌

‌ volume ‌

∴ mass /weight of methanol =0.793gmL−1×20mL=15.86g
Similarly weight of solution
=0.964gmL−1×80mL=96.4g
We know that,
% by weight =‌

‌ weight of solute ‌

‌ weight of solution ‌

×100
=‌

15.86g

96.4g

×100=16.45