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?

$(i)$ Magnesium burns in air with a dazzling light to form $MgO$ and $Mg_{3}N_{2}$.
$2Mg + O_{2} \xrightarrow{\Delta} 2MgO$
$3Mg + N_{2} \xrightarrow{\Delta} Mg_{3}N_{2}$
$(ii)$ Quick lime $(CaO)$ combines with silica $(SiO_{2})$ to form calcium silicate (slag).
$CaO + SiO_{2} \xrightarrow{\Delta} CaSiO_{3}$
$(iii)$ When chlorine is added to slaked lime,it gives bleaching powder.
$Ca(OH)_{2} + Cl_{2} \longrightarrow CaOCl_{2} + H_{2}O$
$(iv)$ Calcium nitrate,on heating,decomposes to give calcium oxide,nitrogen dioxide,and oxygen.
$2Ca(NO_{3})_{2(s)} \xrightarrow{\Delta} 2CaO_{(s)} + 4NO_{2(g)} + O_{2(g)}$