Question

Which of these phase changes requires energy?

A Boiling water on a stove
B Making dry ice from carbon dioxide gas
C Freezing water into ice
D Condensing water vapor to rain

Answer 1

A

Step-by-step explanation:

You have to give energy away for B. You have to think about that carefully. The CO2 starts out with a great deal of energy (mostly KE) and has to slow down to go from gas to a solid. Not B

In general C is the same way. Water has more energy than ice. Not C

Same principle in D. Not D.

So it's A