Answer:
uh A.)? [ZnCI2+H2]? /////////
Answer is: C. nuclear fission.
Nuclear fission is a nuclear reaction or a radioactive decay where nucleus of atom split into smaller ligher nuclei.
Nuclear fission is exothermic reaction which release large amounts of energy (electromagnetic radiation or as kinetic energy, which heat reactors where fission reaction take place).
Electrons move in what is called an electron cloud. Each atom has its own electron cloud associated with it. This region simply represents an area or likelihood within that an electron of corresponding energy can be found within.
The answer gonna be: 1/2^n = 1/2^4 = 0.0625
So, 6.25% sample has not decayed yet!!!