13. Which of the following has the shortest bond length? (A) O22- (B) O2- (C) O2 (D) O2+

15. A 4.2-g oil sample is burned in a bomb calorimeter, which causes the temperature of the calorimeter to increase by 5.0°C. The calorimeter contains 1.00 kg of water (heat capacity of H2O = 4.184 J/g°C) and the heat capacity of the empty calorimeter is 0.10 kJ/°C. How much heat is released per gram of the oil when it is burned? (A) 5.1 kJ/g (B) 10.2 kJ/g (C) 21.4 kJ/g (D) 42.0 kJ/g