Question

A white salt on heating decomposes to give brown fumes and yellow residue is left behind name the salt. And write the reaction involved

Answer 1

The chemical name of white salt is Lead nitrate Pb(NO3)2.
The salt on heating produces brown fumes. This implies that the salt contains nitrate ion. This salt can be any nitrate but if the residue left after heating is yellow in colour implies that the salt is lead nitrate.
The equation involved can be shown as:
2Pb(NO3)2 → 2PbO + 4NO2 + O2

Answer 2

This crystalline salt on heating decripitates and decomposes to form 3 compounds.
As observed experimentally, this salt is lead nitrate [Pb(NO3)2].
The brown fumes are of nitrogen dioxide (NO2).
Yellow residue is lead oxide (PbO).
Reaction
2Pb(NO3)2 ------heat------› 2PbO + 4NO2 + O2

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