# A co-ordination complex compound of cobalt has the molecular formulae containing five ammonia molecules, one nitro group and two chlorine atoms for one cobalt atom. One mole of this compound produces three mole ions in an aqueous solution on reacting with excess of  $AgNO_3,AgCl$  precipitate. The ionic formula for this complex would be: Option 1) $[Co(NH_3)_5(NO_2)Cl_2]$ Option 2) $[Co(NH_3)_5Cl][Cl(NO_2)]$ Option 3) $[Co(NH_3)_4(NO_2)Cl][(NH_3)Cl]$ Option 4) $[Co(NH_3)_5][(NO_2)_2Cl_2]$

S satyajeet

As we have learned

Secondary Valency -

These are non- ionisable and satisfied by neutral or negative molecules

- wherein

eg:

$\left [ Co\left ( NH_{3} \right )_{6} \right ]^{3+}$

Secondary Valency is 6.

The most probable complex which gives three moles ions in aqueous solution may be $[Co(NH_3)_5NO_2]Cl_2$ because it gives two chlorine atoms on ionisation.

$[Co(NH_3)_5NO_2]Cl_2\rightarrow [Co(NH_3)_5NO_2]^{2+}+2Cl^{-}$

Option 1)

$[Co(NH_3)_5(NO_2)Cl_2]$

Option 2)

$[Co(NH_3)_5Cl][Cl(NO_2)]$

Option 3)

$[Co(NH_3)_4(NO_2)Cl][(NH_3)Cl]$

Option 4)

$[Co(NH_3)_5][(NO_2)_2Cl_2]$

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