[" A compound contains three elements "A,B" and "C," if the oxidation number of "A=+2,B=+5],[" and "C=-2," the possible formula of the compound is: "],[[" (a) "A_(3)(B_(4)C)_(2)," (b) "A_(3)(BC_(4))_(2)],[" Consider the following four elements,which are represented according to long form of "]]