Paristalsis moves food along the digestive track involuntarily. When the food moves thought the esophogas, what change is occuring? a. Chemical change
b. Physical Change
c. Both physical and chemical change

Two friends at different locations want to communicate with each other by sending low energy signals. which of the following methods can they use to communicate? a) produce x-rays using colliding electrons and send them to radios, which capture sound b) send messages using infrared radiation, which travel in the form of waves c) send radio waves through intervening media like radio and television d) produce sound waves using microwaves from heated objects

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

What is the most stable monatomic ion formed from nitrogen