A 2.00 g marshmallow is combusted under a flask containing 50.0 g of water at an initial temperature of 25.0oC. After the combustion of the marshmallow, 0.30 g of charred marshmallow remained and the temperature of the water increased to 75.0oC. If the energy associated by the combustion of the marshmallow is 2.5 kilocalories. What is the percent error if the packaging label says that there are 3.5 kilocalories per gram of marshmallow.

Specific heat of water is 4.184 J/goC or 1 cal/goC

PLEASE HELP