Charlie is frying an egg in a pan located over a gas burner. He develops a model to determine the energy produced by the flame in the gas burner by calculating the energy absorbed by the egg. Which assumption will Charlie need to make in order for his model to be considered a closed system?

no but i do not usually comment or use my voice that much when it comes to social media

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.