¿Cuál es la velocidad de una onda electromagnética que tiene una frecuencia de 5.6 x 10 8
Hz y una longitud de onda de 3.44 x 10-3 m?

The answer is solid copper 

Remember that rust prevented by placing a sacrificial electrode in electrical contact with the iron. the sacrificial electrode must be composed of a metal that  oxidizes  more easily than iron (that is, it must be below iron in table 18.1).

Polyethylene is a strong synthetic polymer that can be used to make toys and bottles. this makes plastics which are important also to people but sometimes it lead to harmful environmental effects such as global warming if these plastics are burned.