The percent by mass of potassium in K3Fe(CN)6 is 35.62%.
Ice is the solid phase of water, so it is not silicate.
Atomic mass of Potassium = Mass of 1 atom of Potassium = 39.1 amu
Then
Mass of 6.02 x 1023 atoms of potassium = 39.1 x 6.02 x 1023 amu
=
We already know that
1 mole = 6.02 x 1023 atoms
Also
Number of mole = mass in grams/ atomic mass
Then
Mass in gram = Number of mole x atomic mass
= (39.1 x 6.02 x 1023)/(6.02 x 1023)
= 39.1 g
The correct option among all the options that are given in the question is the third option or option "B".