Question

The diagram below shows the different phase transitions that occur in matter.


Three bars are shown labeled Solid, Liquid, and Gas. They are connected by arrows labeled 1 to 6. Arrow 1 points from liquid to gas; arrow 2 from solid to liquid, arrow 3 from solid to gas, arrow 4 from gas to liquid, arrow 5 from liquid to solid, and arrow 6 from gas to solid.


Which best describes the process that arrow 1 represents?
Molecules are speeding up during boiling.
Molecules are depositing as ice on a surface.
Molecules are slowing down during condensing.
Molecules are moving from stationary positions.

Answer 1

"Molecules are speeding up during boiling."

Arrow 1 is liquid → gas (vaporisation/boiling), where molecules gain kinetic energy and move faster to escape into the gas phase.