Among the following species, the one which is known to exist is:

Step-by-step solution

Let us analyze the existence of each species: [ SiCl ₆]²⁻ does not exist because six large chloride ions cannot be accommodated around a relatively small silicon atom due to severe steric hindrance. Also, the interaction between lone pairs of chloride ions and silicon is not very strong. NCl ₅ does not exist because nitrogen belongs to the second period and lacks vacant d-orbitals in its valence shell, restricting its maximum covalency to 4. PbI ₄ does not exist because the Pb-I bond initially formed does not relea