Question

name the sodium compound which is used for softening hard water

Answer 1

hey friend,
here's your answer,
the compound is sodium carbonate.
hope it helps you.....!!

Answer 2

Sodium Hydroxide can be used. As water contains metallic ions, NaOH dissociates in water and provides -OH ions which combines with metallic ions and forms salts which then precipitate.
This is also called Water Softening.