What is the concentration (molarity) of a solution where 149g of kcl is dissolved in enough water to get a total volume of the solution that is 500mls?

Molar mass KCl = 74.55 g/mol

Number of moles:

mass KC / molar mass

149 / 74.55 => 1.998 moles 

Volume in liters: 500 mL / 1000 => 0.5 L 

Therefore:

M = moles / volume

M = 1.998 / 0.5

M = 3.996 mol/L⁻¹