Deduction u/s 80g - donation to ngos n charitable trusts

Every year I keep donating to different Charitable Instittions(Religious Temples), NGOs (Give India, World Vision...).

I understand that two different categories, viz. 50% and 100% exemption exist.  Now how do I know that my donation is elible for which category in the absence of clear cut mentioning by the Donee Entity. Where can I get the list of Donees eligible for 50% and 100% ?