A compound is two or more elements combinded together.
A element is a pure substance.
it looks like all of them are compounds except the carbon dixode, My teacher would accept that as a anwser idk bout urs thoughs.
The distance is 17 and the displacement is 1
15x 9.8 x .3 = 44.1
15 x 9.8 x 1 = 147
147 - 44.1 = 102.9J
102.9 J
The molecules which evaporate presumably take heat away from the liquid. So, I'd disagree with the classmate. Whether the amount of cooling would differ from the usual case wherein the molecules have different speeds is another question.
I guess the argument goes something along the lines of that the faster moving and therefore most kinetically energetic molecues evaporate and take away most heat. But if there's no faster moving molecules, 'cos they all have the same speed well, then presumably they'd all take away the same amount of heat. So, maybe the cooling would be less. No cooling though ??? Hmmmm dunno .... i think not ....