$A, B$ and $C$ are three elements which undergo chemical reactions according to the following equations:
$A_{2}O_{3} + 2B \rightarrow B_{2}O_{3} + 2A$
$3CSO_{4} + 2B \rightarrow B_{2}(SO_{4})_{3} + 3C$
$3CO + 2A \rightarrow A_{2}O_{3} + 3C$
Answer the following questions with reasons:
$(a)$ Which element is the most reactive?
$(b)$ Which element is the least reactive?
$(c)$ What is the type of reactions listed above?

(B) is the most reactive element.
Reason: $B$ displaces both $A$ and $C$ from their respective compounds,which indicates that $B$ has a higher reactivity than both $A$ and $C$.
$(b)$ $C$ is the least reactive element.
Reason: $C$ is displaced by both $A$ and $B$ in the given chemical reactions,which indicates that $C$ has the lowest reactivity among the three.
$(c)$ These are displacement reactions.
Reason: In each reaction,a more reactive element displaces a less reactive element from its compound.