Modern masonry fireplaces are based on designs first developed

a. during the little ice age
b. in the late 1800s
c. after wwii
d. in this decade

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.

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.