What is the difference between random decay and theoretical?

Spontaneous and random. Decay is called spontaneous because the occur on their own and are unaffected by external factors like temperature, pressure, and many more. Decay is called random because we cannot determine the rate at which it decays but can only determine the probability of the decay.Oct 21, 2015

Explanation:

c is the answer because when something is left after something evaporates that shows the chemical change.