What is the chemical formula of gypsum?

How is bleaching powder prepared? Why does bleaching powder $(i)$ not dissolve completely in water?

State the chemical property in each of the following cases,on which the following uses of baking soda are based:
$(a)$ Applied on an ant stung area.
$(b)$ As a constituent of baking powder.
$(c)$ In soda-acid fire extinguisher.

Write balanced chemical equations for the following:
$(i)$ Bleaching powder is kept open in air.
$(ii)$ Blue crystals of copper sulphate are heated.
$(iii)$ Chlorine gas is passed through dry slaked lime.

Identify the correct representation of the reaction occurring during the chlor-alkali process.

One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is