The question makes no sense, as the questionnaire can only be "validated" when the interviewee has completed it.

Also, I remind you that opinion polls leave the time they find.

Caveat that this isn't something I usually work with, and a lot has been written on the topic. But there's a decent list of steps here: https://www.methodspace.com/blog/validating-a-questionnaire

Hi Mehdi Ait Aammi Hadi, Use a questionnaire that is already tested and validated. For example the International physical activity questionnaire.