Question

why pbcl4 act as strong oxidizing agent

Answer 1

This happens because +2 oxidation state is more stable than +4 oxidation state due to the 'inert pair effect'. As we go down the group, the size of the atom increases as d and f electrons are far away from the nucleus. This makes the s electrons more tightly bound to the nucleus due to which they are reluctant to take part in chemical reactions. They act as an inert pair of electrons and this leads to increased stability of +2 oxidation state in group 14 elements. Instead of losing 4 electrons (2 from s orbital and 2 from p), they only tend to lose the p orbital electrons. Hence Pb⁴⁺ can easily gain 2 electrons to form more stable Pb²⁺ ions thereby acting as a strong oxidising agent.