Abaseball has a mass of 140 grams and a softball has a mass of 280 grams. in which of the following situations would they both have the same momentum?

You haven't suggested any situations. As far as we know from the question, they're both still sitting on the shelf or in a bag somewhere, and their momenta are equal ... both zero. Momentum=(mass) x (speed). As long as the less massive ball is traveling at least twice as fast as the more massive one, its momentum is the same or greater than that of the softball.

Liquid. good luck : )