Answer:- HBr is limiting reactant.
Solution:- The given balanced equation is:

From this equation, There is 2:6 mol or 1:3 mol ratio between Al and HBr. Since we have 8 moles of each, HBr is the limiting reactant as we need 3 moles of HBr for each mol of Al.
The calculations could be shown as:

= 24 mol HBr
From calculations, 24 moles of HBr are required to react completely with 8 moles of Al but only 8 moles of it are available. It clearly indicates, HBr is limiting reactant.
It's classified as an acid
K value of water is 1x 10^-14
Well, Coke is just carbon in chemical reaction, so I think you get:
3 C + 2 As2O3--> 4 As + 3 CO2. Hope this helps! :)