Which of the following statements is true about conductors?

Conductors, such as metals, are characterized by their ability to efficiently transfer electrical current due to the presence of free-moving valence electrons. The correct statement mentions that conductors usually possess 1 or 2 valence electrons. This is important because the presence of fewer valence electrons allows these electrons to move freely within the metal lattice, making it easier for electric current to flow.

In metals, the outermost electrons are not tightly bound to their respective atoms, which contributes to the high electrical and thermal conductivity associated with these materials. Elements from groups 1 and 2 of the periodic table, including sodium and magnesium, exemplify this behavior, further supporting the assertion that conductors have 1 or 2 valence electrons.

The other statements do not accurately reflect the characteristics of conductors. For instance, having 7 or 8 valence electrons would make an element more likely to be an insulator or semiconductor, as these electrons are typically more stable and not readily available for conduction. Similarly, claiming that conductors have no valence electrons or more than 8 valence electrons is inconsistent with the fundamental properties that define conductive materials.