Question

# Name two metals which will displace hydrogen from dilute acids and two metals which will not.

Hint: This question is based on the reactivity of metals placed in the electrochemical series. We will write the electrochemical series; on the basis of that displacement of hydrogen can be determined.

Now, we know as mentioned it is based on the reactivity series of metals.
If we talk about the displacement of hydrogen from dilute acids, then we can say that metals placed above the hydrogen will displace hydrogen.
Now, some metals placed below the hydrogen will not displace the hydrogen; as they are less reactive than the hydrogen.
So, aluminium, and magnesium, or any other metal placed above hydrogen can be considered as an example of the metals that displace hydrogen from dilute acids; and mercury, and silver are the metals which will not displace hydrogen.
The reaction is shown below-
Reaction of Metal with Acid
$\text{Metal + Acid}\to \text{Metal Salt+ Hydrogen}$
\begin{align} & Example \\ & \begin{matrix} Magnesium \\ Mg \\ \end{matrix}\begin{matrix} +HydrochloricAcid \\ HCl \\ \end{matrix}\to \begin{matrix} MagnesiumChloride \\ MgC{{l}_{2}} \\ \end{matrix}+\begin{matrix} Hydrogen \\ {{H}_{2}} \\ \end{matrix} \\ \end{align}
$\begin{matrix} Alu\min ium \\ Al \\ \end{matrix}\begin{matrix} +HydrochloricAcid \\ HCl \\ \end{matrix}\to \begin{matrix} Alu\min iumChloride \\ AlC{{l}_{3}} \\ \end{matrix}+\begin{matrix} Hydrogen \\ {{H}_{2}} \\ \end{matrix}$
$\begin{matrix} Mercury \\ Hg \\ \end{matrix}\begin{matrix} +HydrochloricAcid \\ HCl \\ \end{matrix}\to \text{No Reaction}$
$\begin{matrix} Platinum \\ Pt \\ \end{matrix}\begin{matrix} +HydrochloricAcid \\ HCl \\ \end{matrix}\to \text{No Reaction}$
In the last, we can conclude that aluminium, and magnesium will displace hydrogen from dilute acids; and mercury, and silver will not displace.