Achange in the properties of matter where chemical bonds are broken and new bonds are formed is

a.) a chemical change
b.) a physical change
c.) an ionic change
d.) a covalent change

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.