15. What is one problem that must be overcome before nuclear fusion reactions that produce energy on our planet are a reality? a. Scientists must determine how to control the reaction
b. A company must first apply for a patent
c. Cars have to be redesigned
d. There is not enough open space available in the United States

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.