(4) PCl5--> PCl3+ Cl2 is the correct answer because we both have 1 P atom and 5 Cl atoms on both sides, and thus the masses of the elements don't change.
Hope this would help~
The layer that doesn't exist at all is the l<u>ithosphere</u> because the very last level of the entire atmosphere is the exosphere.
Arsenic is a pure element. Elements (atoms) are the simplest building blocs excluding smaller elementary particles such as electrons, neutrons, quarks, protons etc.
This means that Arsenic can not be broken down any further by chemical change, only nuclear decay can cause the breakdown of large elements into smaller ones. Chemical change would be the combination of multiple elements into a compound or the decomposition of a molecule/compound into pure elements or smaller compounds.
Noble gasses have full outer shells giving them 8 electrons
