Question: Which of the water samples described below has the greatest average kinetic energy per molecule?

  Options: 
 A. 1 liter of ice at a temperature of -50°C
 B. 10 liters of ice at a temperature of -75°C
 C. 1 liter of water at a temperature of 75°C
 D. 10 liters of water at a temperature of 50°C 
Answer: C