Temporary hardness may be removed from water by adding

The surface tension of which of the following liquids is maximum?

Which of the following substances is used in the laboratory to dry natural gas quickly?

What is Calgon,used for softening 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 $146 \, g \, mol^{-1}$)

Heavy water $(D_2O)$ freezes at which temperature (in $^oC$)?