No, the biosphere does not exhibit a clear boundary as life always comes to an end.
The biosphere comprises all the living things of the world, like all the plants and animals. It is considered as the global ecosystem, that is, the gathering of all the planet's ecosystems. It comprises the land and the atmosphere. It is usually considered as the zone of life, where all the species of the planet thrives.
I believe the answer is carbon atoms
They react to form salt ZnCl + hydrogen gas
You multiply the number of atoms by 12 to get how many electrons (since each atom has 12 electrons in it)
you multiply the number of atoms by 13 to get how many neutrons
(since each atom of this isotope has 13 neutrons in it)