In what chapters can you find a rhetorical questions?I been able to find only one question, in chapter eight: "What coud you make of that?", that...

Rhetorical questions are used for a number of reasons. 
Sometimes they are used for dramatic effect, to spur emotion and thought in the listener
as in persuasive arguments.  However, in F. Scott Fitgerald's The Great
Gatsby, a novel dominated by the motif of illusion and superficiality, the
rhetorical questions asked by certain characters seem more often to underscore this
motif. 

That the rhetorical questions are silly or a
superficial way of deliberating with oneself is evidenced in the character of Daisy
whose question to her little girl, whom she has prayed would be "a little fool" is
ridiculous.  When the child appears and is introduced to her company which includes
Gatsby, Daisy asks,

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Did mother get powder on you old yellowy
hair?....How do you like mother's
friends?

Daisy's superficial
way of deliberating with herself occurs also in Chapter One
when Nick asks Daisy if she knows his neighbor in West Egg, Jay
Gatsby:

Gatsby?...What
Gatsby?

In addition to
Daisy's use of rhetorical questions, their employment as a form of dramatic effect is
exemplified in Chapter Five with the character of Jay
Gatsby, who, in his attempt to impress Nick as he and Gatsby wait on the lawn for Daisy
asks,

My house
looks well, doesn't it?...See how the whoe front of it catches the
light.

In
Chapter Eight, as Nick and he go out onto the porch after
breakfast and the garderner announces that he is going to drain the pool, Gatsby tells
him not to do it this day.  Turning to Nick, apologetically, Gatsby
says,

"You
know, old sport, I've never used that pool all
summer?"

Of course, the
dramatic irony of this question, too, is that the pool is the location of Gatsby's
demise.