Hydrogen can be displaced from a lot alkaline solution by

Hydrogen can be displaced from an alkaline solution by more reactive metals in a single displacement reaction. This is based on the reactivity series of metals, which is a list of metals arranged in order of their decreasing reactivity.

In the given options, we have Fe (iron), Cu (copper), Cn (an uncommon abbreviation for carbon, likely meant to be carbon), and Sn (tin). Among these metals, Fe is the most reactive, and it can displace hydrogen from an alkaline solution. This is because iron is higher in the reactivity series than hydrogen, while copper, carbon, and tin are lower in reactivity. The higher the metal is placed in the reactivity series, the more likely it is to displace hydrogen from an alkaline solution.

Here is an example of a single displacement reaction involving iron and an alkaline solution:

\(2Fe + 6NaOH \rightarrow 2Fe(OH)_3 + 3H_2\)

In this example, iron reacts with sodium hydroxide (an alkaline solution) to form iron(III) hydroxide and hydrogen gas. The hydrogen gas is displaced by the more reactive iron metal.

Based on the reactivity series, Fe (iron) is the correct option for displacing hydrogen from an alkaline solution.