sample of hard water contains 122 ppm . what is the weight required to remove it ?

Dear Student,
1 ppm contains the mass of solvent 10⁶ times the mass of solute.
For example 1 mg of solute in 1 kg of water.
1 kg of water = 10³ g water
1 g = 10³ mg 
So, 1 kg of water ​ = 10⁶ mg of water
Hence 1 mg of solute in 10⁶ mg of water.
So, 122 ppm of hard water means 122 mg weight of water should be removed.  
Regards