Sunspots Are decreased temperature areas. So it might be bright all around the sun spots, and the dark spots are where the temperature is lower. They usually form in polar pairs, meaning that on the other side in the same spot there would be another sunspot
I'm assuming that you are asking a general question because you did not include an example.
The limiting reagent is the item in the reactants (reagents) that will run out first. This is because it limits what the reaction can produce, essentially causing the leftover elements/compounds to just sit there.