Question

Which sample of ethanol has particles with the highest average kinetic energy?

(1) 10.0 mL of ethanol at 25°C
(2) 10.0 mL of ethanol at 55°C
(3) 100.0 mL of ethanol at 35°C
(4) 100.0 mL of ethanol at 45°C

Answer 1

the answer is two. All you are looking for with highest average kinetic energy is the one with the highest temperature. In this case it is 10mL ethanol at 55 degrees Celsius.

Answer 2

The second one.
Remember, temperature is the AVERAGE kinetic energy. So, looking for highest average kinetic energy means looking for highest temperature, which is 55.
Note: the amount of the substance does not determine the average kinetic energy.