Which best describes a molecule?
1.a unit made of different kinds of elements.
2.a unit made of only one kind of element
3.a unit made of two or more atoms
4.a unit made of a single atom

answer: you could do some invislibe ink.

explanation: i will tell you how to if u answer my question.

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.

if it's not useful, feel free to report for mistake in answer.