Question

Which substance decreases the hardness of water

Answer 1

Soluble salts of calcium and magnesium change into insoluble salts due to the treatment with sodium carbonate (washing soda).

hope it is helpful to you.

Answer 2

HEYA MATE

UR ANSWER IS HERE

THE SUBSTANCE USED IS

$na2 co3$

OR WASHIMG SODA

AND BOILING WATER IS

ALSO A WAY

HOPE IT HELPS
^_^
MARK AS BRAINLIEST