On a potential energy diagram for the following processes, which of the following has an increase in entropy? a. ice melts b. water freezes c. steam condenses d. water cools down in a refrigerator

A. ice melts

Explanation: Entropy is the measure of randomness. A molecule with high disorder has high entropy.

When ice melts, solid changes to liquid and thus the molecules become more disordered.

When water freezes, liquid changes to solid, and thus the molecules become more ordered.

When steam condenses, gas changes to liquid and thus molecules become more ordered.

When water cools down in a refrigerator, liquid changes to solid, and thus the molecules become more ordered.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.