Jawabanmu

2014-06-12T17:27:40+07:00
X mol = (3 x 10^20) / ( 6.12 x 10^23)
x mol = 3 / 6120
= 1 / 2040

mol = massa / Ar
1/2040 = x / 63,5
x = 63,5 / 2040