Among the elements listed, which one could replace all the rest as an ion from a compound in aqueous solution?
A) Ag
B) Fe
C) Ca
D) Cu

Answer : The correct option is, (C) Ca

Explanation :

Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.

It is represented as,

In this reaction, A is more reactive element and B is less reactive element.

Reactivity series : It is used to determine the products of the single displacement reactions. As we know that in a single displacement reaction, the most reactive metal displaces the least reactive metal.

From the given reactivity series we conclude that,

Calcium (Ca) metal is more reactive metal than all the rest metals (Ag, Fe, Cu). So, Ca metal can displaces all the rest metals from its solution.

Hence, the correct option is, (C) Ca