If we take the 1st case in which iron piece is put inside water, then surely the iron piece would float on water as density of iron is greaterthan water.
But in second case the density of mercury is greaterthan iron due to which iron piece will sink in water.
Answers & Comments
HEY MATE!
If we take the 1st case in which iron piece is put inside water, then surely the iron piece would float on water as density of iron is greater than water.
But in second case the density of mercury is greater than iron due to which iron piece will sink in water.
Hope it helps
HAKUNA MATATA :))