Heating solid ammonium chloride involves change in the  

Arrange the following sequence in order to derive the formula of zinc oxide.

(1) The valencies of ions formed by zinc and oxygen are written below without positive and negative sign.

(2) The positive ion, i.e., ${\mathrm{Zn}}^{2+}$ followed by the negative ion, i.e., oxide $\left({\mathrm{O}}^{2-}\right)$ ion are written with their charges.

(3) The valencies of zinc and oxide ion have common factors, and hence, they are divided by their highest common factor.

(4) The magnitude of valencies of the ions should be interchanged and written as subscripts on right side of the respective ions.