<span>molar mass of MgCl2
= 24.32 + 2 x (35.45) = 95.22 g</span><span>
<span>16.4g MgCl2 x (1 mol MgCl2/95.22
g MgCl2) = 0.172 mol MgCl2 </span>
</span>
<span>0.172 mol MgCl2 x (6.022 x 10^23/1 mol
MgCl2) = 10.36 x 10^22 atoms<span> </span></span>
I'm not sure what you mean. Besides, I feel like you're talking math.
But anyways, if you have 120 let's say
The scientific notation is 1.20 × 10^2
if you have 125000
the scientific notation is 1.25 × 10^ 5
The number of times you go left the decimal, I guess exponent increases
So yea
Potassium +calcium sulphate ------> K2SO4+Ca