What must happen for heat to be transferred by thermal conduction A. Two molecules must collide with each other.
B. The sun must send out electromagnetic waves.
C. The kinetic energy must be equal in two objects.
D. The liquid or gas must circulate to move the heat.

B. The sun must send out

Explanation:

ljjjljlj kjlk,ljym jlyu; jm; l mumytj

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.