How many grams are in 3.0 moles of H2O

18x3=54 gram

Explanation:

When you express molecular mass (in case of molecule)/atomic mass(in case of atom) in gram it will be equivalent to one mole. For example:

12 gram Carbon atom = 1 mole of Carbon atom = N number of Carbon atom

16 gram Oxygen atom= 1 mole of Oxygen atom = N number of Oxygen atom

32 gram Oxygen molecule (O2) = 1 mole of Oxygen molecule (O2) = N number of Oxygen molecule (O2)

similarly 1 mole of water is equivalent to molecular mass of water x 3 that is 18x3=54 gram. It would constitute 3N molecules of water.

N: Avogadro's number : 6.022140857 × 10^23

c, liquids evaporate, creating a gas