Answer:
2.55×10²⁰ atoms of Mo are contained in 40.6 mg
Explanation:
1 atom of Mo has a mass of 1.59×10⁻²² g
So let's think a rule of three for this question.
Firstly, we convert the mass in mg to g
40.6 mg / 1000 = 0.0406 g
In the mass of 1.59×10⁻²² g, there is 1 atom of Mo
In the mass of 0.0406 g there are (0.0406 / 1.59×10⁻²²) = 2.55×10²⁰ atoms
