What is the atomic radius in picometers of an argon atom if solid argon has a density of 1.623 g/cm3 and crystallizes at low temperature in face-centered cubic unit cell

4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temperature drops from 22.0 c to 16.9 c. assume that the specific heat of the solution is the same as that of pure water. calculate delta(h) (in kj/mol nh4no3) for the solution proces.