For an atom to be electrically neutral the number

For an atom to be electrically neutral, the number of protons and electrons must be the same

Explanation: if the number of protons and electrons are the same, then the atom will be electrically neutral. For example if an atom have 5protons and 5electrons, then +5 protons will cancel out - 5electrons making the net charge of the atom to be zero(neutral)

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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