(07.01 LC)
Which statement is true about endothermic and exothermic reactions?
Kinetic energy is absorbed and converted to potential energy in an endothermic reaction.
Kinetic energy is absorbed and converted to potential energy in an exothermic reaction.
Energy is released in an endothermic reaction
Energy is absorbed in an exothermic reaction
Question 21 Multiple Choice Worth 5 points)
(08.04 MC)

Option A

Explanation:

In an exothermic reaction, energy is released while in an endothermic reaction energy is taken in. This is because in endothermic reaction, the energy required to break the bonds of reactant molecule is much higher the energy released as of the formation of new bonds in the product.  

Also in an exothermic reaction, potential energy is converted to kinetic energy while in endothermic reaction kinetic energy is converted into potential energy  

Thus, option A is correct

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.