There is no limit for google ads on multiple sites. Yes you definitely can use your one adsense account on your all web sites that you have.
Just think it as it is very simple that if you can not use one adsense acount on multiple sites then would you use multiple adsense acounts on multiple sites ?
Simply if google doesnot allow a single person to have more than one account then could there be any distinction that a person can use one adsense acount which can be used for one domain only?
So, Be tension free and you can use your one adsense account in all of your sites/blogs
but they must be according to TOS, and may not be violating adsense terms and conditions