Early in Harper Lee's To Kill a Mockingbird, after being told by Atticus that a lot of people around town are saying he shouldn't defend Tom Robinson, Scout asks one question that reflects her own naive understanding and the difficult situation Atticus is in for having agreed to defend Robinson:

If you shouldn't be defendin' him, then why are you doin' it? (Ch. 9)

Scout's question reflects her naive belief that if a large majority of people express an opinion, their opinion must be the right one. However, as Scout comes to understand later in the story, the majority of the people are actually wrong, and Atticus is right in his decision to defend Robinson. Therefore, Scout's question also reflects the difficult position Atticus is in. Not only must Atticus defend Robinson before the jury in his trial, he must defend himself against the townspeople for his decision. Yet, as Atticus explains to Scout, he is willing to place himself in such a difficult position because he knows it is the right thing to do.

A second question Scout asks further reflects the difficult position Atticus is in:

Atticus, are going to win it? (Ch. 9)

Atticus knows that the inevitable answer to that question is, "No, honey," due to the fact that racism is abundant in the town. Yet, he also knows that just because they will lose the case doesn't mean it isn't worth trying to win. He further knows that attempting to win the case is the right thing to do since no concrete evidence exists to convict Robinson. Scout's question, followed by her unfinished question, "Then why--," further reflects Atticus's difficult position: In defending Robinson, Atticus is swimming upstream, moving against the grain of society, and he is doing so because he knows it is the right thing to do, regardless of inevitable failure.

In Harper Lee's To Kill a Mockingbird, what questions does Atticus ask the jury in Tom Robinson's trial?

In Chapter 20 of Harper Lee's To Kill a Mockingbird, the trial of Tom Robinson is coming to a close.

The witnesses have all been called and cross-examined. Atticus has begun to address his closing remarks—his summation—to the jury. He begins by stating that the case against Tom Robinson should never have come to trial. He reminds the jury that Mayella Ewell had done something terrible in throwing herself at Tom and trying to kiss him. Because she had broken this time-honored code within society, to ease her own guilt...

...she tried to put the evidence of her offense away from her...he must be removed from her presence, from this world. She must destroy the evidence of her offense.

Atticus then asks the jury the rhetorical question:

What was the evidence of her offense?

He answers:

Tom Robinson, a human being.

Next Atticus asks:

What did she do?

He answers: 

She tempted a Negro.

As he continues describing what transpired with the testimony, Atticus then asks:

What did her father do?

Here Atticus notes that no one can be certain of exactly what Bob Ewell did when he discovered his daughter, but that evidence indicated a left-handed man “savagely” beat Mayella. (At this point, everyone in the room knows that her father is left-handed.)

Each of these questions points the jury to specific and important points that Atticus wants to refresh in each of their minds before they go to into deliberations, hoping that they will rely on the facts and not the lies thrown at Tom Robinson's behavior and character in the show put on by the Ewells, or prejudice: that...

...in our courts all men are created equal.