Question

$$\begin{gathered} A+BX\to AX+B \\ B+CX\to Noreaction \\ C+DX\to Noreaction \\ C+AX\to CX+A \end{gathered}$$

Identify the least reactive metal among A, B, C and D and give reason.

Answer 1

Metal reactivity series

The series which arranges metals in the decreasing order of reactivity is known as metal reactivity series.

$$\begin{gathered} \text{·The reactivity series is based on nature of the reaction between metals and substances like air, water and acids.} \\ \text{·The metals placed near the top of the series are most reactive, while those placed near the bottom are least reactive.} \\ \text{·A more reactive element can displace a less reactive element from its salt solution.} \\ \text{1. A+BX→AX+B} \\ \text{In the above reaction A displaces B from BX. Therfore A is more reactive than B.} \\ \text{2.B+CX→No reaction} \\ \text{B cannot displaces C from its salt solution. Therefore B is less reactive than C.} \\ \text{3.C+DX→No reaction} \\ \text{C cannot displace D from its salt solution. So C is less reactive than D.} \\ \text{4.C+AX→CX+A} \\ \text{C can displace A from its salt solution.} \\ \text{So C is more reactive than A.} \\ \text{But C cannot displace D.} \\ \text{D is more reactive than C.} \\ \text{Hence the reactivily order is B<A<C<D} \end{gathered}$$