When 0800 G of NH₄NO₃ Was Added to 150

Multiple Choice

When 0.800 g of NH₄NO₃ was added to 150.0 g of water in a styrofoam cup, the temperature dropped by 0.413°C. The heat capacity of H₂O is 4.18 J/g°C. Assume the specific heat of the solution equals that of pure H₂O and that the calorimeter neither absorbs nor leaks heat. What is the molar heat of solution of solid NH₄NO₃?

A) +260. J/mol
B) -2.60 kJ/mol
C) +2.60 kJ/mol
D) +26.0 kJ/mol
E) none of these