You can find the answer to part (a) in this Socratic answer, so I'll just help you out with part (b).
So, you know that the theoretical yield for this reaction is
Now, you perform this reaction with this info in mind and find that the reaction produced
The reaction's percent yield essentially tells you how much product you actually get for every
#color(blue)(|bar(ul(color(white)(a/a)"% yield" = "what you actually get"/"what you should theoretically get" xx 100 color(white)(a/a)|)))#
All you have to do now is plug in your values to find
#"% yield" = (6 color(red)(cancel(color(black)("g"))))/(35.4color(red)(cancel(color(black)("g")))) xx 100 = color(green)(|bar(ul(color(white)(a/a)color(black)(17%)color(white)(a/a)|)))#
The answer is rounded to two sig figs.
This tells you that for every