Question

why there is difference in sound on dropping a matter and a piece of coal

Answer 1

this due to air resistance and the coal is not as tensile as metal

Answer 2

A metal is a material (an element, compound, or alloy) that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. About 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids.