Does Google AdSense approve free domain?
With a free domain, you are not allowed to register to google adsense. you need to have a registered domain name. Even after you have a registered domain, you might not still get approved.
  1. Sign in to your AdSense account.
  2. Click Sites.
  3. In the list of sites, find your site and check its status. Tip: Use the filter. at the top of the page to quickly find sites in your sites list. You can either use the preset terms or enter your own search term. Status. What it means
How to Apply for a Google AdSense Account
  1. You're at least 18 years old.
  2. You have an active Gmail account that isn't already linked to an AdSense account.
  3. You have a live website that meets all of Google's terms of service requirements.
  4. Your website is at least three (3) months old

But more specifically, here are the three types of sites you should aim to create if you want to earn AdSense revenue.
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3 types of sites that have quality AdSense revenue
  1. A blog site. ...
  2. A forum site. ...
  3. A free online tool site.