Question

A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present in one gram of
this sample of gold? [Au = 197]

Answer 1

1g sample = 0.9 gram gold + 0.1 gram copper

so 197 gram have 6.022 * 10^23 atom of gold so just find for 0.9gram had how much atom

197 --------> 6.022 * 10^23 atom
0.9 -------> ?

0.9 * 6.023*10^23
______________ = 2.7*10^22

197

Answer 2

I hope you will understand my writing.