Which of the following cannot show geometrical isomerism?[Cr(H2O)4Br2]+[Cr(H2O)5Br]2+[Cr(H2O)3Br3][Cr(H2O)4BrCl]+

Geometrical isomerism, also known as cis-trans isomerism, is a form of stereoisomerism. It is observed in square planar and octahedral complexes.

1. [Cr(H2O)4Br2]+: This is an octahedral complex where the chromium is surrounded by 4 water molecules and 2 bromine atoms. It can show geometrical isomerism as the bromine atoms can either be adjacent to each other (cis) or opposite to each other (trans).

2. [Cr(H2O)5Br]2+: This is an octahedral complex where the chromium is surrounded by 5 water molecules and 1 bromine atom. It cannot show geometrical isomerism as there is only one type of ligand (water) and one bromine atom.

3. [Cr(H2O)3Br3]: This is an octahedral complex where the chromium is surrounded by 3 water molecules and 3 bromine atoms. It can show geometrical isomerism as the bromine atoms and water molecules can either be adjacent to each other (cis) or opposite to each other (trans).

4. [Cr(H2O)4BrCl]+: This is an octahedral complex where the chromium is surrounded by 4 water molecules, 1 bromine atom, and 1 chlorine atom. It cannot show geometrical isomerism as there is only one type of ligand (water) and one bromine atom and one chlorine atom.

So, the complexes [Cr(H2O)5Br]2+ and [Cr(H2O)4BrCl]+ cannot show geometrical isomerism.