Lead chromate is yellow in color due to their absorption and reflection of specific wavelengths of light.
PbCrO4+NaOH(hotexcess)→[Pb(OH)4]−2+Na2CrO4
The complex formed is [Pb(OH)4]2−
which has coordination number =4 and complex is dianionic due to presence of (−2) charge.
coordination number, the number of atoms, ions, or molecules that a central atom or ion holds as its nearest neighbours in a complex or coordination compound or in a crystal.