The reaction for producing glucose in plants, called photosynthesis, is:
6co2 + 6h2o light > c6h12o6 + 6o2.
1. if a plant produces 6.86 mol c6h12o6 , how many moles of h2o are needed?

41.16 moles of H2O

Explanation:

Ratio for the products-reactants is 1:6, so 1 mol of glucose is produced when plants use 6 moles of water.

Then, let's make a rule of three:

1 mol of glucose is produce by using 6 moles of water

6.86 moles of glucose are produced by the use of (6 . 6.86)/1 = 41.16 moles of H2O