Many first aid kits include an instant cold pack. A cold pack utilizes a chemical reaction that has a significant change in energy in order to make the pack feel cold. Explain which type of reaction, an endothermic reaction or an exothermic reaction, would be most useful for making a cold pack.

Question 3(multiple choice worth 4 points) (04.04 lc) what does it mean when an element is reduced? it empties a valance shell, reducing its atomic radius. it gains electrons, reducing its overall charge. it increases electronegativity, reducing its ability to bond. it loses electrons, reducing its electron number.

Helium decays to form lithium. which equation correctly describes this decay?

Which of these is a density dependent factor? a. epidemic b. earthquake c. drought d. hurricane