Which type of chemical reaction tends to occur on its own, or spontaneously?

A reaction is called spontaneous when it takes place of its own accord without any external help. It is an exothermic reaction and it is a spontaneous reaction . Above examples show, both exothermic and endothermic reactions could be spontaneous.

thermophiles, notice the prefix thermo.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.