Questions & Answers about كان الطفل جائعا وعطشان.
Why is جائعا in the accusative case (ending in -an) here?
This happens because of the verb كان (was). When you use كان, the subject of the sentence (الطفل) stays in the default nominative case, but the predicate, which is the word that describes the subject, changes to the accusative case. That is why جائع gets the double fatha ending and an added alif to become جائعا.
Since عطشان (thirsty) is also describing the child, why doesn't it have an alif at the end like جائعا?
They are both in the accusative case, but عطشان is a special type of word called a diptote. Diptotes are words that never take tanwin (the double vowel sound at the end of a word). Many adjectives ending in ـان fall into this category. Because it cannot take a double fatha, it just takes a single fatha on the final letter and doesn't need an extra alif.
How would the endings change if the sentence was in the present tense ('The child is hungry and thirsty')?
In Arabic, present tense 'is' statements don't use a verb. Without كان to change the endings, the adjectives revert to the default nominative case. The sentence would be الطفل جائع وعطشان. In pronunciation, جائع takes a double damma and loses the alif, while the diptote عطشان takes a single damma.