Yes you can and in fact you should. I have been using the same adsense account for all my sites and blogs.
Yes you are allowed only one adsense account. Having duplicated accounts can get you banned as Google is very strict with this.
I suggest that you use 2 different adsense. the one will serve as your back up in case you got into trouble with Google adsense.
Yes, you can use 1 for any number of site... But, you will not get benefit of Advanced reporting feature...
This is very simple and so basic Answer is YES Sure Why not, WELCOME to Adsense World so You can do it immediately.
You can use one google adsense account for event thousands of sites if you have them. Of course your pages should comply the TOS.
you can use 1 account show ads in unlimited sites but you can not show more that 2 adsense id account ads on a single site.
Hey Guys I have done the same as you all told me. why google ads not showing on my blog home page.whenever i open inner page then it shows up. whats wrong with this bog. Is there i m missing something ???????? Blog showing in my signature.........