Do Hamlet's soliloquies, by revealing his inner thoughts, confirm his nobility?
This depends massively on your own view of Hamlet. You need to ask yourself what precisely you think about him as a character. On the one hand, it is possible to say that his soliloquies reveal him to be a particularly angst-ridden, disillusioned young man who is thoroughly fed up with life. Consider his soliloquy in Act I scene 2, for example:
O, that this too too solid flesh would melt
Thaw and resolve itself into a dew!
Or that the Everlasting had not fix'd
His canon 'gainst self-slaughter! O God! God!
How weary, stale, flat and unprofitable,
Seem to me all the uses of this world!
If you take this view of Hamlet's character, you would look at the way in which his soliloquies are used to reveal his character and particularly his distaste with his life and his desire to end it. Also, you would examine the way in which he constantly berates himself in his soliloquies whilst at the same time seeking to justify his procrastination. Hamlet is a character who, in so many ways, is defined by his inability to act, and his soliloquies explore this aspect of his character further.
However, at the same time, if we take a more sympathetic view of Hamlet, we could argue that his soliloquies are vehicles that show his immense nobility as he tries to work out what to do and what is right in terms of how he responds to the Ghost's accusation. This is something that can particularly be seen in the following quote:
Hamlet, in his determination to try and prove the guilt of Claudius before acting, shows himself to be a noble character.