why the metals are lustrous???????//

Metals are lustrous because of the presence of free electrons. As we know that metals have a tendency to lose electrons, the outermost electrons are loosely bound and easily break away from metal atoms. These electrons can freely move about the surface of metal and are therefore called mobile electrons. Because of these mobile electrons, light falling on the surface of a metal is not transmitted but  is reflected,and hence the metals appear lustrous.

@ Nikita, good attempt. Keep it up.