'free' is either 'libre' or 'gratuit' in French.

('libre' when it is related to freedom; 'gratuit' when you mean 'at no expense')

An acte gratuit is an impulsive act which lacks a motive.

Is it free in French is est-il gratuit. This is because es-il is is it in English and free in french is gratuit. So that adds up to est-il gratuit.

voudriez-vous un (...) gratuit ? aimeriez-vous un (...) gratuit ?

The English translation of the term "test gratuit" means "free test". The term comes from French with the word "gratuit" meaning "free" and the obvious translation of the word "test".