What are the main organ systems and what are their purposes?

Chalk is an ionic compound. which is a property of all ionic compounds that makes chalkboard? particularly useful for writing on a a high melting point hardness and brittleness inability to dissolve in water a multicolored appearance

Cpr, or cardiopulmonary resuscitation, is a first-aid technique to save lives. it involves compressions of the patient's chest cavity. which description is the best description of the functions of chest compressions in cpr? chest compressions are done to pump the heart. chest compressions are done to strengthen the rib bones. chest compressions increase carbon dioxide inhalation. chest compressions allow the patient's muscles to wake up.

Several billion years ago which gas was the least prevailant in the atmosphere