Question

What do you understand about the reactivity series of metals? Write the name of one metal of each which is more reactive and less reactive than hydrogen.

Answer 1

The reactivity of metals can be defined by the stability of ions, as more the stability ion is more will be the reactivity. Reactivity series is the representation of metals according to their reduction potential or oxidation potential.

Complete step-by-step answer: Reactivity of metal decrease with increase reduction potential therefore metals with more negative reduction potential will displace other metals with less negative reduction potential from their salt solution.
Those metals which have negative reduction potential can liberate hydrogen gas from acid and water except with $HN{O_3}$ which oxidise ${H_2}$ gas to ${H_2}O$ and itself reduce to $N{O_2}$ exceptionally only $Mn$ and $Mg$ can liberate ${H_2}$ gas from dilute or very dilute $HN{O_3}$.
Reactivity series or activity series according to increasing reduction potential as we move downward-
$L{i^ + }/Li \\\ A{l^{ + 3}}/Al \\\ Z{n^{ + 2}}/Zn \\\ F{e^{ + 2}}/Fe \\\ S{n^{ + 2}}/Sn \\\ P{b^{ + 2}}/Pb \\\ {H^ + }/{H_2} \\\ C{u^{ + 2}}/Cu \\\ S{n^{ + 4}}/S{n^{ + 2}} \\\ F{e^{ + 3}}/F{e^{ + 2}} \\\ A{g^ + }/Ag \\\$
On moving down the group reactivity of metals decreases and reduction potential increases. Down the group oxidising nature increases. The elements on the top can be easily corrode and can react with cold water.
Reduction potential for hydrogen is zero and for metals above hydrogen is negative and for metals below hydrogen is positive. It shows that lithium has a maximum tendency to oxidise and silver has a maximum tendency to reduce.
Lithium is more reactive than hydrogen. While silver is less reactive than hydrogen. Hydrogen is taken as standard for the calculation of reduction potential as it has zero reduction potential, so we can calculate reduction potential of different elements with respect to hydrogen.

Note: $Zn,Sn,Fe$ with $HN{O_3}$ exceptionally form ${N_2}O$ while other metals with $HN{O_3}$ produce $N{O_2}$.
All reactions in which elements with less reduction potential undergo oxidation and other elements with high reduction potential undergo reduction, are always spontaneous.