Use of don't/ de qui

Question

In the following sentence, "La chaise, don't/ de laquelle tu as cassé le pied, est maintenant inutile," I interpreted it to mean whose leg you broke and thus answered don't / de qui and not de laquelle. Why am I wrong?

Cécile Janty-Davies · Accepted Answer

Hi Ann, 
De qui  only applies to living things , so you can't use it for a chair...
Take a look at the following lesson for further information -
https://french.kwiziq.com/revision/grammar/de-qui-duquel-de-laquelle-dont-of-about-whom-relative-pronouns

Ron Thomas · Answer

Je devine que la leçon dont vous parlez soit cela "De + qui, duquel, de laquelle, dont = Of/about whom (relative pronouns)".  
I think it would be helpful to look at possible translations:
dont tu as cassé le pied = which you broke the foot
de laquelle tu as cassé le pied = of which you broke the foot
de qui = of who(m)  [ de qui (of/about whom), which can only apply to living things ]
Cela m'apparait que dont et de laquelle sont les réponses plus exactes.

Bonne chance,
Ron