The isoelectronic pair is

Identify the thermal decomposition reactions that evolve a gas containing an equal number of $\sigma$ and $\pi$ bonds.
$(a)$ $BeCO_3 \xrightarrow{\Delta } BeO + CO_2$
$(b)$ $Fe_2(SO_4)_3 \xrightarrow{\Delta } Fe_2O_3 + 3SO_3$
$(c)$ $FeSO_4 \xrightarrow{\Delta } Fe_2O_3 + SO_2 + SO_3$
$(d)$ $(NH_4)_2Cr_2O_7 \xrightarrow{\Delta } Cr_2O_3 + N_2 + 4H_2O$
$(e)$ $ZnSO_4 \xrightarrow{\Delta } ZnO + SO_3$
$(f)$ $NH_4Cl \xrightarrow{\Delta } NH_3 + HCl$

The formal charges of atoms $(1)$,$(2)$ and $(3)$ in the ion $[\underset{(1)}{O}=\underset{(2)}{N}=\underset{(3)}{O}]^{+}$ are:

Which of the following pairs of molecules is isoelectronic as well as isostructural?

Which of the following molecules or ions possesses electrovalent,covalent,and coordinate bonds at the same time?

Amongst the following,the total number of species $NOT$ having $8$ electrons around the central atom in its outermost shell is $NH_3$,$AlCl_3$,$BeCl_2$,$CCl_4$,$PCl_5$: