I have a lot of pages which contain a picture and few lines of text(20-50 words), can I put adsense on those pages?
surely you can and i dont think you will get any problem in have any type of adds - either image or text so not to worry and have a blast
You can if the pages follow the TOS. It is advisable to place ads on pages with sufficient text to get targetted ads and also, to avoid smartpricing.
Put a product from a affiliate program related to topic on site that way it has something else than adsense