I think iron because the other options are all bad conductors.
Galactic recycling is a natural phenomenon in which the stars expel some gas into the space so that it would mix with the interstellar medium. As a result, this would produce new younger stars. So, basically, the concept done here is the mass and energy conservation. In order to create new species, the energy must come from another source.
It called cation, Well, When an atom gains or loses an electron, it
attains a net charge and becomes an ion. When electrons are lost, the
resulting ion is called cation and when electrons are gained, the
resulting ion is called an anion. So, Cations have a net positive
charge, while anions have a net negative charge. it is true.
V1 / T1 = V2 / T2
3.5 / 20 = 3 / T2
T2 = 17.1 C
