The answer is A, because of the chemical reaction taking place color can change (as in this case). Hope it helps!
Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g)
Oxidation means lose of electrons and increase of positive charge so the part which oxidized in this equation is Zn(s) because it converted to Zn²⁺ (i.e. lost two electrons)
We know 1 mole of any atom or molecules contains 
atom or molecules.
1 mole of HBr i.e 81 gm/mol contains atom or molecules.
So, mass of 
molecules is :
Therefore, mass of molecules is 1.21 gm .
Hence, this is the required solution.
Protons: 12
Neutrons: 13
<span>Electrons: 12</span>
