D Irrational Numbers
Work Step by Step
Even if we forgot this relationship, we can solve this problem using process of elimination. In other words, if we were not sure, we could create an example to test the answer. $2 \times \sqrt 2 =2.828427125...$ (Recall, $\sqrt 2 $ is a irrational number). 2.828427125... is not a whole number, rational number, or an integer, so we know that an irrational number (like $\sqrt 2 $) times a rational numer (like 2) will not always be a rational number, whole number, or integer. This eliminates answers A, B, and C, leaving us with the correct answer—D.