What is characteristic of physical and chemical reactions?
A) They involve changes in energy, but not in matter.
B) They involve changes in matter, but not energy.
C) They always require energy.
D) They sometimes emit energy.

Question

What is characteristic of physical and chemical reactions? 
A) They involve changes in energy, but not in matter. 
B) They involve changes in matter, but not energy. 
C) They always require energy. 
D) They sometimes emit energy.

Quizplus · Accepted Answer

Physical and chemical reactions can sometimes emit energy, such as in exothermic reactions where energy is released in the form of heat or light.

What Is Characteristic of Physical and Chemical Reactions