Answer:
Aluminium
Explanation:
When a body is immersed in a liquid partly or wholly it experiences an upward force which is called buoyant force.
The amount of buoyant force depends on the volume of body immersed, density of liquid and the value of acceleration due to gravity.
Here, the density of liquid is same in both the cases and g be the same. So, here the amount of buoyant force depends on the volume of body immersed.
As the density of lead is more than the density of aluminium, so the volume of aluminium is more than lead, as volume is equal to mass divided by density. So, the buoyant force acting on the aluminium is more than lead.
Answer:
Let No be initial no of atoms
N = N0 / 2 after 1 half-life
N = N0 / 4 after 2 half-lives
So after 2 half-lives 20 of the 80 atoms remain
