Question

When crystals of lead nitrate are heated s in a dry test tube

• A. crystals immediately melt
• B. a brown residue is left
• C. white fumes appear in the tube
• D. a yellow residue is left

Answer 1

The correct option is D

a yellow residue is left

Explanation for correct option

• $2\mathrm{Pb}\left({\mathrm{NO}}_3\right)\to 2\mathrm{PbO}+{\mathrm{NO}}_2+{\mathrm{O}}_2$
• Lead nitrate, on heating strongly in a dry test tube, produces Lead oxide($\mathrm{PbO}$), Nitrogen dioxide( ${\mathrm{NO}}_2$) and oxygen(${\mathrm{O}}_2$).
• The lead nitrate turn yellow residue due to the resultant product- lead oxide($\mathrm{PbO}$) and the evolution of a reddish-brown gas which is nitrogen dioxide.
• The reaction carried out on heating lead nitrate crystals is a decomposition reaction. When lead(II) nitrate is heated, it breaks down or decomposes into yellow colour lead (II) oxide, colourless gas of oxygen and brown colour nitrogen dioxide.