Cryolite, na3alf6(s), an ore used in the production of aluminum, can be synthesized using aluminum oxide. start this question by first balance the chemical equation.

Unbalanced chemical equation of synthesizing cryolite:

Al₂O₃ + NaOH + HF → Na₃AlF₆ + H₂O.

Balanced chemical equation:

Al₂O₃ + 6NaOH + 12HF → 2Na₃AlF₆ + 9H₂O.

According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.  

There are two aluminium atoms (Al), six sodium atoms (Na), eighteen hydrogen atoms (H), nine oxygen atoms (O) and twelve fluorine atoms (F) on both side of balanced chemical reaction.

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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