Set theory problem

Let $A$ , $B$ , $C$ and $Y$ be subsets of $X$ and define the application ${ f }_{ Y }:P(X)\longrightarrow P(X)$ given by ${ f }_{ Y }(A)=A△Y=(A∪Y)∖(A∩Y)$ , where $P(X)$ denotes the power set of $X$ . Which of the following statements hold true?

1. The application is bijective
2. $(A△B)△C=A△(B△C)$
3. ${ f }_{ A }\circ { f }_{ B }={ f }_{ B }\circ { f }_{ A }$
4. The application is not surjective