<u>Answer:</u> The correct answer is the number of moles of chlorine molecules needed to balance the equation.
<u>Explanation:</u>
A balanced chemical equation follows law of conservation of mass.
This law states that mass on either side of the reaction remains constant. Also, mass can neither be created, nor be destroyed, but it can only be transformed from one form to another form.
In the given chemical equation:
![2Al(s)+3Cl_2(g)\rightarrow 2AlCl_3(s)](https://tex.z-dn.net/?f=2Al%28s%29%2B3Cl_2%28g%29%5Crightarrow%202AlCl_3%28s%29)
The numbers '2', '3' and '2' represents the number of moles of the specie required to balance a chemical equation.
Here,
is a molecule of 2 chlorine atoms.
Hence, the correct answer is the number of moles of chlorine molecules needed to balance the equation.