Answer:
A. It's a 'clean' energy. Your cooch need a cleanup
So the equation is balanced, meaning they have the smallest amounts of each element in the reactants to create the products.
So, 2 moles of H2S (the coefficient) contributes to 2 moles Ag2S, which is why the ratio is 2:2.
I hope that made sense.
Answer:
112.2L
Explanation:
Volume (V) = 300g
Temperature (T) = 822K
Pressure (P) = 0.9atm
using the ideal gas equation;

Molar gas constant (R) = 
Mole (n) =
Molar mass of Mercury = 200.59g/mol

= 1.496mol
Now, the volume can be calculated;
V = 
∴Volume of mercury = 
2H2O+O2--->2H2O2
8.5 gm H2O2=0.25 mole
hence H2O is also 0.25 mole i.e.4.5 gm
O2is 0.125 mole i.e.4 gm