For the unit cell shown, how many chloride ions (bigger circles) and sodium ions (smaller circles) are there per unit cell, respectively [if not sure, review calculation for.

the answer is 0.42 is that is an option. this question provides no info

i belive it is water

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.