How many water molecules are in a 0.341 g sample

for my answer, i got: 0.1139E23 or 1.139E24

The molar mass of H2O is 18.02g/mol and Avogadro's number is 6.022E23. Using this information we can figure it out like so:
0.341g H2O/18.02= .0189 moles H2O.
.0189 moles H2O x 6.022E23= 1.139E22 molecules H2O
I double checked that so I know it is right! You probably just made a slight calculation error on your second possible answer.

First we need to know the molar mass of water.

16.00+2(1.008) = 18.016g/lol

Now divide your sample size by this

0.341÷18.016 = .018927619

Now multiplu by Avogadro's number
.0189276199×(6.022×10^(23)) = 1.1398212703E22

Double check on the internet for the value of Avogadro's number. I'm not sure of the exponent. Other than that, the answer should be numerically the same but may be off by a factor of 10.

What's the molar mass of water?
That's how many mols are in that many grams

Then how many molecules in a mol is Avogadro constant....

1.1396 E 22