Which of the following compound is both paramagnetic and coloured?

\(VOSO_4\)

The correct answer is option 2.\(VOSO_4\).

\(VOSO_4\) is paramagnetic because it has one unpaired electron in the vanadium ion \((V^{4+})\). It is also coloured because the unpaired electron can absorb energy from visible light, causing the compound to appear blue.

The other answer choices are not both paramagnetic and coloured.  \((NH_4)_2[TiCl_6]\)is diamagnetic, \(K_2Cr_2O_7\) is coloured but diamagnetic, and \(K_3[Cu(CN)_4]\) is diamagnetic and colourless.