There are two tests that an adjective should pass.
First, modification by very and pretty. This test may not be applicable in all cases, but where variations in degree are possible, it's a pretty good one.
*His current state would most likely have been very/pretty alleviated.
Second, use as a predicative complement in a complex-intransitive or complex-transitive clause (your student may know these as 'linking verb' constructions).
?His state remains alleviated.
*The treatment made his (current) state alleviated.
Note that the passive is possible with some verbs of this sort if we insert a be verb. But, then we'd be using a different construction.
His state seems to have been alleviated.
For alleviated, both tests lean pretty heavily in favor of a verb. But, sometimes the tests are inconclusive and it's ambiguous whether the word in question is an adjective or a past participle.
Her leg was broken. [adjective or past participle?]
In these cases it's useful to ask whether the context indicates a state or an event.
Her leg was (*pretty) broken in a car accident. [past participle]
Her leg was (pretty) broken last time I saw her. [adjective]
There are, of course, stative interpretations of verbs as well, so this is not always useful.
When it comes to entitled as a single word, it could go either way. However, when a to... phrase is added it loses the ability to be modified by very. So in the context given it's probably best considered a verb.
Everyone is very entitled.
*Everyone is very entitled to respect and dignity.
The two sentences above, similar to many adjective / past-participle contrasts, also have a difference in definition for entitled - spoiled vs giving a rightful claim to possession, privilege, etc.