Which of the following changes can alter the form of a substance but does not necessarily change it to the other substance? a. physical changes b. pressure changes c. phase changes d. all of the above

D - by undergoing all of these changes you would still be left with the same substance

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.