21. Which substance is a gas at 45 degrees C?* A. Ethanol O B. Hexane C. Methane O D. Methanol

power out to power in less than 100%

there are no contact forces mentioned on the list of choices that you've provided.

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach