17. Metallic silver crystallizes in a cubic close-packed arrangement in which the silver atoms occupy all of the corner

[answerhappygod]

17. Metallic silver crystallizes in a cubic close-packed
arrangement in which the silver atoms occupy all of the corner and
face-center positions on the unit cell. X-ray crystallography
experiments have determined that the unit cell edge length is 407
pm. Assume that the electron cloud of the silver atoms define the
boundary of the atoms, and that when the atoms pack in the unit
cell the outer electron clouds touch the neighboring atoms. Given
this information, what is the radius of a silver atom? (1 m = 1012
pm; 1 m = 1010 ˚A). (a) 407 pm (b) 144 pm (c) 50.9 pm (d) 1.44 pm
(e) 0.0475 pm
The correct answer is B 144 pm
can you please explain why and explain the formula is one was
used