AdSense for mobile allows webmaster to generate earnings from their mobile webpages using Adsense ads. You’ll earn money whenever your mobile website’s visitors click on your ads. Google has some rules that you must follow before adding Google Adsense ads on your mobile website.
AdSense for mobile ad code will not display ads on standard webpages.
Only one AdSense for mobile ad unit may be displayed per mobile webpage.
Google ads displayed on a publisher’s mobile-compliant webpage may not be modified or obscured in any way.
A “double” ad unit can only be placed on the bottom of the page, but may appear above the page’s footer (e.g. navigational links, copyright messages, etc.).
After a user click, display of the advertiser’s landing page may not be interrupted or prevented in any way. For instance, publishers may not display their own interstitial pages before taking users to the advertiser’s website. Link.