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Plaster of paris is a hemihydrates of $CaS{O}_4$ obtained by heating the gypsum around 300 K

Sodium carbonate is used in softening of hard-water

Sodium peroxide reacts with cold water giving hydrogen peroxide

The mobilities of the alkali metal ions in aqueous solutions are $L{i}^{+}>N{a}^{+}>K^{+}>R{b}^{+}>C{s}^{+}$