The atomic radius of metal x is 125 picometers (pm) and a crystal of metal x has a unit cell that is face-centered cubic. calculate the density of metal x (atomic weight = 42.3 g/mol).

I guess you mean 1.40 x 10^2 pm. An FCC cell contains 4 atoms, and the face diagonal embraces two atomic diameters. So the face diagonal of the Metal X cell is 560 pm, and the edge of this cell is 560 pm/sqrt(2) = 396 pm. The volume of the cell is 6.21 x 10^(-29) m^3, and the mass of the cell is 4*42.3 g/(6.022E23) = 2.81 x 10^(-22) grams or 2.81 x 10^(-25) kg. The density of metal X is:
2.81E(-25)kg/6.21E(-29)m^3 = 4525 kg/m^3 or 4.525 g/cm^3.

Atp, shorthand for adenosine triphosphate, is the standard molecule for cellular enger in the human body. all motion and metabolic  processes  within the body begins with energy that is released from  atp, as its phosphate bonds are broken in cells through a  process  called hydrolysis.