• # question_answer Amongst the following the compound that is both  paramagnetic and coloured is A)  ${{K}_{2}}C{{r}_{2}}{{O}_{7}}$                B)  ${{(N{{H}_{4}})}_{2}}[TiC{{l}_{6}}]$        C)  $CoS{{O}_{4}}$                    D)  ${{K}_{3}}[Cu{{(CN)}_{4}}]$

In ${{(N{{H}_{4}})}_{2}}[(TiC{{l}_{6}})],$ $T{{i}^{4+}}(3{{d}^{0}}\,\,4{{s}^{0}})$ has no unpaired electrons. In ${{K}_{2}}C{{r}_{2}}{{O}_{7}},C{{r}^{6+}}$ $(3{{p}^{6}}{{d}^{0}})$ has no unpaired electrons. In $CoS{{O}_{4}},\,C{{o}^{2+}}({{d}^{7}})$ has unpaired electrons in d-orbitals, so it is both paramagnetic and coloured. In ${{K}_{3}}[Cu{{(CN)}_{4}}],C{{u}^{+}}(3{{d}^{10}}),$ has no unpaired