Explanation:
(a) According to the given data, mass of the solution will be calculated as follows.
Mass of solution = Mass of KCl + Mass of water
= (40 + 225) g
= 265 g
Therefore, (m/m)% of KCl will be calculated as follows.
(m/m)% of KCl =
= 
= 15.09%
Hence, mass percent of KCl in the solution is 15.09%.
(b) Now, we will calculate the mole fraction of ionic species present in KCl in the solution are follows.
Molar mass of KCl is 74.55 g/mol.
Moles of KCl = 
= 
= 0.536 mol
or, = 0.54 mol
As, molar mass of water is 18 g/mol. Hence, moles of water will be calculated as follows.
Moles of
= 
= 
= 12.5 mol
So, total number of moles = moles of KCl + moles of 
= (0.54 + 12.5) mol
= 13.04 mol
Calculate the mole fraction of KCl in the solution as follows.
Mole fraction = 
= 
= 0.041
Therefore, mole fraction of the ionic species KCl in the solution is 0.041.