Physical. When you simply desolve something with water, to don't actually change it. This action can be undone.
An example of a chemical reaction is when the cells within completely change. You you burn wood, you can't go back in time and un-burn it. Does that make sense?
.035 gallons equals 0.1324894 L
The first option is the correct.
Since we know the mass of one atom of Fe is 56 and that of Cl2 atoms is 71 (one atom has 35.5 mass) hence both of them will be consumed