I just had this question on a quiz and I'm not sure what I did wrong.

Question: Calculate the number of hydrogen atoms in 0.125 g of citric acid H3C6H5O7

Heres what I did..

I found the percent composition of hydrogen to be 4.17%, then I found the total moles of hydrogen in citric acid and multiplied it by 0.0417 (this is where I think i went wrong), then multiplied that number by avagadros number to get 1.63 X 10^19 particles.

Anyone care to correct me and provide right answer?

Thanks.