Find the approximate atomic mass of a water molecule (h2o). give your answer in atomic mass units rounded to the nearest whole number.

First step is to get the mass of water molecule in grams:

From the periodic table:

molar mass of hydrogen is 1

molar mass of oxygen is 16

molar mass of a water molecule = 2 (1) + 16 = 18 gm

Now, to convert the gm into amu, all you have to do is multiply the gm you got by Avogadro's number as follows:

mass of water molecule = 18 x 6.22 x 10^23 = 1.1196 x 10^25 amu which is approximately 1 x 10^25 amu