I don't understand can someone help me

Define dew point. i am writing this part to be able to ask the question

How are isotopes of the same chemical element alike? how are they different?

Which of the following is the correct definition of chemical energy? a. energy an object has because of its motion or position b. energy resulting from the flow of charged particles, such as electrons or ions c. energy produced from the splitting of atoms d. energy stored in chemical bonds of molecules