In the sentence 'The rational is rewarded'. Why is rational an adjective in the sentence.

Because the word "rational" takes on the function of modifying the noun, in addition to representing a characteristic.

Explanation:

Adjectives are words that accompany a noun and modify it, adding a characteristic that particularizes that noun. In this case, we can say that in the sentence above, the word "rational" is the adjective, since it specifies what is "rewardable".

It should be noted that adjectives accompany nouns in number, gender and degree.

- "the die is cast; i have consented to return if we are not destroyed. thus are my hopes blasted by cowardice and indecision; i come back ignorant and disappointed. it requires more philosophy than i possess to bear this injustice with patience. i have lost my hopes of utility and glory; i have lost my friend."

the answer is camped