Answer:
12
Step-by-step explanation:
6H2O or hexahydrate is a group of 6 water molecules or 6 molecules of dihydrogen monoxide. When looking for the total particular number of elements in a substance, find the subscript or smaller number in front of that atom, and look out for the coefficient or bigger number of the whole substance, and multiply that coefficient by the subscript to find the total atoms of that element.
Since there are 2 hydrogen's in each molecule of water, 6 molecules would make that a total of 12 hydrogen's for 6 molecules of water.