Question

GeX4 is more stable than GeX2 ehereas PbX2 is more stable than PbX4 . why?

Answer 1

Ge, and Pb are the elements of group 14(the Carbon family); in which the unique property showing variable valency due to INNERT
PAIR EFFECT in which the elements from Ge to Pb show the oxidation state +2 and +4. This innert pair effect arises due to the
sheilding of s-electrons by intervening d and f-electrons. Hence, as the no. of d and f-electrons increases down the group from Ge to
Pb the inert pair effect becomes more prominent and so the +4 o. state becomes less stable. 
So, the + 2 o.s of Pb is more