The number of water molecules in gypsum and plaster of paris respectively are

An alkaline earth metal $(M)$ gives a salt with chlorine,which is insoluble in water at room temperature but soluble in boiling water. It also forms an insoluble sulphate whose mixture with a sulphide of a transition metal is called 'lithopone' - a white pigment. Metal $M$ is

$A$ metal $M$ readily forms its sulphate $MSO_4$ which is water-soluble. It forms its oxide $MO$ which becomes inert on heating. It forms its insoluble hydroxide $M(OH)_2$ which is soluble in $NaOH$ solution. Then $M$ is

$A$ salt gives a bright red colour to the flame. This colour indicates the presence of:

Plaster of Paris when mixed with the correct amount of water sets into a solid mass due to the formation of

What happens when:
$(i)$ magnesium is burnt in air
$(ii)$ quick lime is heated with silica
$(iii)$ chlorine reacts with slaked lime
$(iv)$ calcium nitrate is heated?