A nitrate that on heating strongly leaves behind a black residue is a) Zinc nitrate

To determine whether zinc nitrate leaves behind a black residue upon heating, we should consider the thermal decomposition of zinc nitrate.

1. Break Down the Problem:

   • Identify the thermal decomposition products of zinc nitrate.
   • Understand what the black residue might be.

2. Relevant Concepts:

   • The chemical formula for zinc nitrate is Zn(NO₃)₂.
   • Upon heating, zinc nitrate decomposes into zinc oxide (ZnO), nitrogen dioxide (NO₂), and oxygen (O₂).
   • The reaction can be represented as: $2 \text{Zn(NO}_3\text{)}_2 \rightarrow 2 \text{ZnO} + 4 \text{NO}_2 + \text{O}_2$

3. Analysis and Detail:

   • Zinc oxide (ZnO) is a white solid. Thus, the thermal decomposition of zinc nitrate does not produce a black residue. The gas produced during decomposition (NO₂) may appear brown, but that does not contribute to a black residue.

4. Verify and Summarize:

   • After analyzing the thermal decomposition of zinc nitrate, the final products do not include any black substances.
   • Therefore, zinc nitrate does not leave behind a black residue upon heating.

Final Answer

A nitrate that on heating strongly leaves behind a black residue is not zinc nitrate, as it decomposes to form zinc oxide, which is a white solid.