Which part of the human body is more complex your heart of the circulatory system

Is this correct if not can u correct me

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.

What is the average rate of the reaction between 10 and 20 s?