Physical or chemical change? what gave you the idea that it was such?

The answer to your question is Chemical change.

Explanation:

Process

Chemistry classifies changes in two types: physical and chemical changes.

Physical changes occur when matter changes its physical state. Examples are evaporation, condensation, solidification, etc.

Chemical changes occur when matter reacts with another substance and it changes its original composition, a new molecule is formed.

From the description given we conclude that is is a chemical change.

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.