Which of the following salts does not contain water of crystallisation?

What is the chemical formula of gypsum?

$(a)$ Write the chemical name and chemical formula of washing soda.
$(b)$ How is it obtained from sodium chloride? Give equations of the reactions.
$(c)$ Why is it called a basic salt? Give any one of its uses.

Write an equation to show the reaction between Plaster of Paris and water.

Give two important uses of washing soda and baking soda.

Fill in the missing data in the following table:

Name of the salt	Formula	Base	Acid
$(i)$ Ammonium chloride	$NH_{4}Cl$	$NH_{4}OH$	-
$(ii)$ Copper sulphate	-	-	$H_{2}SO_{4}$
$(iii)$ Sodium chloride	$NaCl$	$NaOH$	-
$(iv)$ Magnesium nitrate	$Mg(NO_{3})_{2}$	-	$HNO_{3}$
$(v)$ Potassium sulphate	$K_{2}SO_{4}$	-	-
$(vi)$ Calcium nitrate	$Ca(NO_{3})_{2}$	$Ca(OH)_{2}$	-