Question

I am asking this question again that y a living body sink in water and a dead body float on water???
As i got 16 views at a time

Answer 1

When you’re swimming your lungs contain at least that much air at all times and so you float. If you drown, your lungs fill with water and you sink. But after three days or so, the bacteria in your intestines will have produced that two cola can’s worth of methane and carbon dioxide and you’ll float back to the surface. In very cold water, the bacterial action is slowed down and fish and crabs might eat you first. 

Answer 2

Upthurst.....
Then more the mass of the body the more will be the upthurst .....a body when partially or wholly immerse in a liquid experiences an upward conduction of force....it floats when it's weight = the buyont force and it sinks when it's weight is more.....

Or

When a person dies....the air which was filled in his lungs gets displaced by water by which it's volume increases and thus it sinks down... afterwards the bacteria in the gut and the chest cavity produces enough gas to make it flow to the surface...gases like methane , hydrogen and carbon dioxide ..