Question

why do materials float or sink in water give some examples

Answer 1

Things having density less than that of water floats in it. For example wood,kerosene.
Those having more density sink in water. For example iron

Answer 2

heyaa,,,,
it's all about the concept of density.
Some objects start out with a density of less than water (1 gram per cubic centimeter), so they float naturally (like wood, oil, etc.).
and some objects starts out with a density of more than water so, they sink.
ex; iron, Cooper etc)...
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hope it helps☺☺☺