The axis of the sphere below is 16 units in length. what is the surface area of the sphere? .

There are enough information's already given in the question. Based on those information's that answer can be easily deduced.
Radius of the sphere = 8 units
Then
Surface area of the sphere = 4 *pi * r^2
                                            = 4 * pi * (8)^2
                                            = 4 * pi * 64
                                            = 256pi
I hope that this answer has come to your help.