#### Answer

No. Yes.

#### Work Step by Step

Two vectors add to zero if and only if they have the same length (magnitude) and point in exactly opposite directions.
On the other hand , 3 vectors of unequal magnitude CAN add to zero. For example, a vector 7 cm long pointing due east, added to two vectors of 4 and 3 cm pointing due west will give zero. In two or three dimensions, if the 3+ vectors, added tail-to-tip, gives a closed triangle, quadrilateral, or polygon, then the vector sum is zero.