Ana iya tunanin fashewa, dangane da cika takamaiman ka'idoji masu fashewa.
Don hydrogen ya kunna fashewa, hankalinsa dole ne ya kwanta a cikin wani bakin kofa, daga 4.0% ku 75.6% ta girma. Haka kuma, dumbin tarin zafi a cikin wani yanki mai iyaka yana da mahimmanci ga irin wannan fashewar.