Most of the newspaper (was, were) placed in the recycling can.

i don't know exactly what it's asking, but either one of these pairs would

her; him

edith; sam

hope this ya

type of error:

the error in the sentence is a "dangling modifier". a dangling modifier is a phrase, word or clause that "dangles" because there is not target to modify. in this case, "after mopping the floor" is the dangling modifier since it has no word to modify. the noun "house" cannot mop the floor; therefore there is a mistake in the writing of the sentence.