1. I am too full to eat more.
2. I am too full to eat leftover food.
3. I am too ful to eat all the food.
4. I am too full to eat all the cooked rice.
5. I am too full to eat the leftover food.
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Are they all grammatical? Do we have to use 'rice' or 'cooked rice' here?
#1 says it all!!
#s 3 and 4 are OK, but 1 is best.
As for cooked rice, we don't usually eat raw rice, so "cooked" isn't really necessary, but it's fine to use the word.
Yes, all of the sentences you provided are grammatically correct.
As for the use of "rice" or "cooked rice," both options are acceptable depending on the context and what you want to emphasize.
In sentences 1, 2, and 3, using just "rice" indicates the general concept of rice as a type of food. It doesn't specify whether it's cooked or uncooked rice.
In sentences 4 and 5, by using "cooked rice," you are being more specific and referring to rice that has already been cooked.
The choice between using "rice" or "cooked rice" depends on the level of detail you want to convey. If you want to be more specific about the rice being cooked, you can use "cooked rice." However, if you simply mean any type of rice, whether cooked or uncooked, then "rice" alone would be appropriate.