Is there a chance to place adsense ads on a dot tk free domain.

Don't, it's not allowed for free domains.

Look at the terms and conditions for free domains,

Section 10.3, clause xvii:

Using a FREE DOMAIN with Domain Parking, both monetized and non-monetized.
Domain Parking includes webpages that solely show advertisements and no actual content, “Under Construction” pages, “Coming Soon” pages and  alike

You can of course still do this with *paid* domains though