Find the number of complexes which satisfy at least three of the following four conditions :
(a) Primary valence=3
Secondary valence=6
Oxidation number of central atom `lt +3`
Number of ions per molecule `gt 3`
`I. [Pt(NH_(3))_(4)][PtCl_(6)]," "II. [Co(NH_(3))_(6)]Cl_(3),`
`III. [Co(NH_(3))_(5)(OH_(2))]Cl_(3)," "IV. [Pt(NH_(3))_(6)]Cl_(4),`
`V. K[PtCl_(5)(NH_(3))]," "VI. [CoCl_(2),(en)_(2)]^(+),`
`VII. [Ni(CO)_(4)]," "VII. [Co(EDTA)]^(-)`

Answer

3

Explanation

(II),(III) and (IV) satisfy at least.