Identify the metals will not react with a solution of \[{\text{CuS}}{{\text{O}}_4}\]
A.Fe
B.Zn
C.Ag
D.Mg

Hint: Copper(II) sulphate is an inorganic compound with the chemical formula \[{\text{CuS}}{{\text{O}}_4}_x\] , where x can range from 0 to 5. The most popular type is the pentahydrate. Blue vitriol, bluestone, vitriol of copper, and Roman vitriol are some of the older names for this ingredient.

Complete answer: Metals are arranged in descending order of their reactivities in the reactivity series, which is also known as the reactivity series.
The reactivity sequence provides information that can be used to predict whether a metal can displace another in a single displacement reaction. It can also be used to find out about a metal's reactivity with water and acids.

Since Fe, Zn, and Mg are higher in the activity series than copper, and a metal higher in the activity series displaces the lower ones solution, these metals will react with \[{\text{CuS}}{{\text{O}}_4}\]; however, since Ag is lower in the series than Cu, it cannot displace Cu from the liquid.
\[{\text{Fe}} + {\text{CuS}}{{\text{O}}_4}({\text{aq}}) \to {\text{FeS}}{{\text{O}}_4}({\text{aq}}) + {\text{Cu}}({\text{s}})\]
In this reaction, the highly reactive metal iron oxidises and forms a new compound called ferrous sulphate by replacing the copper in copper sulphate and giving up two electrons.
\[{\text{Zn}} + {\text{CuS}}{{\text{O}}_4}({\text{aq}}) \to {\text{ZnS}}{{\text{O}}_4}({\text{aq}}) + {\text{Cu}}({\text{s}})\]
Zn is added to a copper sulphate solution in the above reaction, and Zn displaces Cu from its salt solution. This is due to the fact that zinc is a more reactive element that displaces fewer reactive metals in its solution.
\[{\text{Mg}} + {\text{CuS}}{{\text{O}}_4}({\text{aq}}) \to {\text{MgS}}{{\text{O}}_4}({\text{aq}}) + {\text{Cu}}({\text{s}})_{}^{}\]
A redox reaction occurs when magnesium is put in copper sulphate solution, allowing copper metal to form on the magnesium and the solution's deep blue colour to fade.

Note:
A reactivity sequence (or activity series) in chemistry is an observational, measured, and structurally analytical progression of a series of metals, ordered from highest to lowest by their "reactivity." It's used to condense detail about metal reactions with acids and water, single displacement reactions, and metal extraction from ores.