Question

why does dead body does not sink in water whereas living body sink in water fully..

Answer 1

because the dead body become swollen after death that's why the dead body float on water.

Answer 2

why does dead body does not sink in water whereas living body sink in water fully?

Dead body floats on water surface while a living body sink into water due to depend on density.

The dead man density lower than water.but the living body having density more than water.

This is the reason why dead body floats in water and living body sink in water.