The major products during the removal of temporary hardness of water are

Heavy water $(D_2O)$ freezes at $............ \ ^\circ C$.

$A$ sample of water contains sodium chloride. It is:

What is "Calgon"? Give its molecular formula.

Which salt does not produce hardness in water?

$100 \, mL$ of a water sample contains $0.81 \, g$ of calcium bicarbonate and $0.73 \, g$ of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of $CaCO_3$ is .............. $ppm$ (molar mass of calcium bicarbonate is $162 \, g \, mol^{-1}$ and magnesium bicarbonate is $146 \, g \, mol^{-1}$)