Explanation:
Le Chatelier's principle states that for a long period of time if a system is at equilibrium and it is subjected to change in concentration, temperature, volume or pressure then the system shifts to a new equilibrium.
This change will partly counter acts the applied change.
Therefore, when heat is added to the system then equilibrium will shift to the side where temperature or heat is reduced again.
For example, 
Since heat is added to the system, hence, system will shift to the left side or we can say equilibrium will shift to the backward direction.
C+2H2 -------> CH4
from reaction 2 mol 1 mol
from the problem x mol 10 mol
x=2*10/1 = 20 mol
Answer: 20 mol of H2.
The answer is: Dividing the number of molecules in the sample by Avogadro's number.
The Avogadro’s number is the number of atoms in 12 grams of the isotope carbon-12 (¹²C).
Na is Avogadro number or Avogadro constant (the number of particles, in this example carbon, that are contained in the amount of substance given by one mole).
The Avogadro number has value 6.022·10²³ 1/mol in the International System of Units; Na = 6.022·10²³ 1/mol.
For example:
N(Ba) = 2.62·10²³; number of atoms of barium.
n(Ba) = N(Ba) ÷ Na.
n(Ba) = 1.3·10²⁴ ÷ 6.022·10²³ 1/mol.
n(Ba) = 2.158 mol; amount of substance of barium.
D, all of these. (this is to reach the word limit on answers ignore it)
A. 2 is the answer let me know if im wrong sorry if i am.
