What is one limitation of a CPR mannequin?

The chest cannot rise and fall when CPR is performed on a mannequin.

Explanation:

In CPR training, one of the main necessities for performing CPR is letting the chest rise and fall.

The reason this detail is important is so you can make sure the victim's lungs are working properly and to see to it that you're completing the resuscitation procedure properly.  

If the chest doesn't rise and fall, it can lead to even more severe problems because first, you may be doing it wrong, or second, there may be a rip or tear in the lung organ or the windpipes.

a polymer is a chainlike molecule made up of small molecular units. these small molecular units are called monomers. monomers of polymer can be joined together either naturally or synthetically.  

1. a tropical dry forest carries out more rapid nutrient cycling