There is some butter and sugar on the bread. are is plural . Think of 2 sentences - There is some butter on the bread. There is some sugar on the bread. Combine those two sentence There is some butter on the bread and there is some sugar on the bread. Now simplify the sentence to reduce words. There is some butter and sugar on the bread. So you want the singular "is" rather than the plural "are". And you use "on" rather than "in" because neither the sugar or butter is part of the bread but is "on" the top of the bread.