$CoSO_{4}Cl \cdot 5NH_{3}$ exists in two isomeric forms '$A$' and '$B$'. Isomer '$A$' reacts with $AgNO_{3}$ to give white precipitate,but does not react with $BaCl_{2}$. Isomer '$B$' gives white precipitate with $BaCl_{2}$ but does not react with $AgNO_{3}$. Answer the following questions.
$(i)$ Identify '$A$' and '$B$' and write their structural formulas.
$(ii)$ Name the type of isomerism involved.
$(iii)$ Give the $IUPAC$ name of '$A$' and '$B$.'

(A) Isomer '$A$' reacts with $AgNO_{3}$ to give white precipitates,indicating the presence of $Cl^{-}$ ions in the ionisation sphere.
$\therefore A = [Co(NH_{3})_{5}(SO_{4})]Cl$
Isomer '$B$' reacts with $BaCl_{2}$,indicating the presence of $SO_{4}^{2-}$ ions in the ionisation sphere.
$\therefore B = [Co(NH_{3})_{5}Cl](SO_{4})$
$(ii)$ The type of isomerism is Ionisation Isomerism.
$(iii)$ $IUPAC$ names:
$A$: Pentaamminesulphatocobalt$(III)$ chloride
$B$: Pentaamminechloridocobalt$(III)$ sulphate