How do two sublevels of the same principal energy

Each energy sub-level corresponds to an orbital of a different shape which describes where the electron is likely to be found

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.

5.6⋅10−^19  j

do you need the explaination?