Differentiate between atoms, elements, molecules and compounds

*urgent

Atoms are the simpliest form of matter. But an atom can be classified as an element and an element can be presented various substance. An element can be oxygen, hydrogen and so on. The combination of two or more elements is a compound. A compound can be a molecule, same as the atom to element.  

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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