A 2.45 g sample of naphthalene (C10H8) is contaminated with a noncombustible material. The heat of combustion of naphthalene is -2.45 x 10^3 kJ/mole. When this sample was burned in a bomb calorimeter, the temperature increased 2.6 C. From previous measurements, the heat capacity of the bomb calorimeter is known to be 10.6 kJ/C. What is the mass percent of naphthalene in the sample?