What is phase change? How does matter change in phase?

Answer ASAP pls :(

If 3 moles of a compound use 24 j of energy in a reaction, what is the a hreaction in j/mol?

Animals that reproduce sexually either do it through external or internal fertilization. read the following statement and decide if it is true or false. birds reproduce through external reproduction which is because the female will then be able to protect the egg.

Which of the following describes the entropy change as a solution is made from a liquid and solid