So,
Our conceptual plan is as follows:
g AlCl3 --> mol AlCl3 --> mol H2 --> g H2

Hope this helps!
Answer:
This is a chemical symbol for Potassium Bromide
··hydrogen peroxide if its wrong sorry i didnt pay atention much but i do remember the elemants being hydrogen peroxide and oxygen and copper so ya ω
1) Carbon-13:
Proton-6 Neutron-7 Electron-6
2)Atomic mass of element X:
(55*10+56*20+57*70)/100=56.6
Answer:
Cu + 4HNO3 ---> Cu(NO3)2 + 2NO2 + 2H2O.
Explanation:
Balancing:
Cu + 4HNO3 ---> Cu(NO3)2 + 2 NO2 + 2H2O.