Why is oxygen spelt o2

it's a diatomic molecule–which is why it is O₂.

Explanation:

Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. Only a handful of elements on the periodic table are diatomic such as nitrogen, hydrogen, fluorine, chlorine, bromine, and iodine.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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