How are the oxides of less reactive metals like silver and mercury reduced?

By thermal decomposition

The correct answer is option 1. By thermal decomposition.

The correct answer for reducing the oxides of less reactive metals like silver and mercury is 1. By thermal decomposition.

Less reactive metals, like silver (Ag) and mercury (Hg), form oxides that are relatively unstable compared to the oxides of more reactive metals.

These unstable oxides can be reduced to the pure metal simply by applying heat. This process is called thermal decomposition.

For example:

Silver oxide $(Ag_2O)$: When heated above $200^oC$, silver oxide decomposes into silver metal and oxygen gas:

$2Ag_2O(s) \longrightarrow 4Ag(s) + O_2(g)$

Mercury (II) oxide $(HgO)$: At around $300^oC$, mercury (II) oxide decomposes into mercury metal and oxygen gas:

$HgO(s) \longrightarrow Hg(l) + O_2(g)$

Other reduction methods:

While thermal decomposition is the most common method for these less reactive metals, other reduction techniques like using reducing agents might be employed in specific contexts. However, for large-scale production or simple purification purposes, thermal decomposition is often preferred due to its simplicity and energy efficiency.

Electrolysis, typically used for highly reactive metals, wouldn't be the most suitable method for silver and mercury oxides due to their ease of reduction by heat.