Question 7 of 10 Which of the following indicates an endothermic reaction?
A. A+B+C+D+ gold
B. A+B + C + D + heat
C. A + B + heat → C + D + heat
D. A + B + heat → C+D

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange

The concentration of ionic substances is important for the heart to beat. your heart responds to electrical impulses that travel through heart cells that are made up mostly of water. which properties of ionic compounds are important to support this function? solubility in water conductivity crystalline melting point