Answer:
↓
Explanation:
It means there is that many number of molecules.
For example, in photosynthesis 6CO₂ is used. The 6 in front of CO₂ is used to show that 6 molecules of carbon dioxide are used as a reactant in the process. If it is 2, then 2 molecules of carbon dioxide are used as a reactant in the process, and so on.
Whatever the number of the coefficient is just expresses how many of those molecules are there.
Hope this answer helps.
