The reaction of an acid with a base, for example, results in the creation of a salt and water. Some, but not all, reactions can be reversed. See nuclear reaction. An action that results directly from or counteracts another action, especially the change in a body's motion as a result of a force applied to it.
Snakes are cold-blooded creatures, just like amphibians. When a certain animal is cold-blooded, it basically means that they are able to adapt their own internal temperature to that of their environment. When a snake is in a cool environment, their body temperature tends to drop rather quickly.
Lizards are cold-blooded animals, meaning they do not have a high enough metabolism to regulate their own body temperatures. This means that globally distribution is higher in the tropics, sparser in temperate regions and entirely nonexistent at the poles.