Consider the energy transfers and transformations that occur when a person rides a bicycle. Describe this process by selecting the correct options from the drop-down menus. Chemical energy is transformed into energy in the person’s muscles. Kinetic energy is from the person’s legs to the pedals. Kinetic energy is thermal energy due to friction when the wheels get warm.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

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.