Which of the following tetrahalides of Group 14 elements is highly unstable and does not exist at room temperature?

Step-by-step solution

In Group 14, the stability of the +4 oxidation state decreases down the group due to the inert pair effect. Consequently, Pb ⁴⁺ is highly unstable and acts as a strong oxidising agent. The iodide ion ( I ⁻ ) is a strong reducing agent. When Pb ⁴⁺ is combined with I ⁻ , an intramolecular redox reaction occurs spontaneously where Pb ⁴⁺ oxidises I ⁻ to I ₂ and is itself reduced to the stable Pb ²⁺ state. Thus, PbI ₄ does not exist and immediately decomposes to PbI ₂ and I ₂ . The other halides listed ( SnI ₄ , GeI ₄ ,