What happens when bleaching powder is heated with dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$? Give the equation of the reaction. 

How many molecules of water of crystallization are present in the following substance? 

Crystal of copper sulphate. 

How many molecules of water of crystallization are present in the following substance? 

Gypsum 
 

How many molecules of water of crystallization are present in the following substance? 

Washing soda 
 

How will you obtain bleaching powder from limestone? Write equations for the reactions involved. 

Give two important uses of washing soda and baking soda each.