Question

The arrows in the chart below represent phase transitions.

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 arrows represent the phase transitions in which heat energy is gained?
1, 2, and 3
2, 3, and 5
3, 4, and 5
4, 5, and 6

Answer 1

Arrows 1, 2, and 3.

Melting (solid → liquid), vaporization/sublimation (liquid → gas and solid → gas) require input of heat (endothermic); the reverse processes release heat.