Which of the following has square planar geometry?

• Correct answer
  A

  $\left[\mathrm{PtCl}_{4}\right]^{2-}$
• B

  $\left[\mathrm{NiCl}_{4}\right]^{2-}$
• C

  $\left[\mathrm{ZnCl}_{4}\right]^{2-}$
• D

  $\left[\mathrm{CoCl}_{4}\right]^{2-}$

Solution

$\left[\mathrm{PtCl}_{4}\right]^{2-}$ has square planar geometry. $\mathrm{Pt}: 5 d^{9} 6 s^{1}$
Two electrons are removed from $5 d$ shell and $6 s$ shell. So, hybridisation takes place is $d s p^{2}$ i.e. square planar geometry.

Hence, the correct answer is option: 'A'.