Understanding Metal Reactivity and Oxide Reduction

This question explores the relationship between a metal's position in the activity series and how its oxide can be reduced to obtain the pure metal. Let's break down the two statements.

Statement I Analysis: Metals Low in Activity Series

The activity series (or reactivity series) of metals arranges metals based on their reactivity. Metals that are very low in this series, such as mercury (Hg), silver (Ag), and gold (Au), are quite unreactive.

• Because these metals are unreactive, their corresponding metal oxides are relatively unstable.
• This instability means that the bond between the metal and oxygen in their oxides is weak.
• Consequently, these metal oxides can often be decomposed simply by heating, without needing a strong chemical reducing agent like carbon or hydrogen. The heat provides enough energy to break the weak metal-oxygen bonds.

Therefore, Statement I, stating that metals low in the activity series can be obtained from their oxides without using any specific reducing agent (implying a chemical reducing agent is not needed), is accurate.

Statement II Analysis: Heating for Oxide Reduction

Statement II builds upon the idea presented in Statement I. It specifically mentions that heating alone is sufficient for the reduction of oxides of these less reactive metals.

• Thermal decomposition is the process where a substance breaks down into simpler substances due to heat.
• For oxides of metals very low in the reactivity series, heating causes this decomposition. For example, mercury(II) oxide decomposes upon heating:

  $2\text{HgO(s)} \xrightarrow{\Delta} 2\text{Hg(l)} + \text{O}_2\text{(g)}$

  In this reaction, the heat ($\Delta$) is sufficient to break down HgO into pure mercury (Hg) and oxygen gas (O₂). No other reducing agent is added.
• Similarly, silver oxide decomposes upon heating.

Thus, Statement II is also accurate, as heating is indeed the method used to reduce these specific metal oxides back to their pure metallic form.

Conclusion

Both statements accurately describe the chemical behavior of metals situated low in the reactivity series concerning their oxides. Their oxides are unstable and can be decomposed into the metal and oxygen simply by heating.