Question

When crystals of lead nitrate are heated strongly 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

Answer

The correct answer is (D) A yellow residue is left.

The reaction is given as follows:

heat

2Pb(NO3)2--------->2PbO+4NO2+O2

Lead nitrate ,when heated strongly in a dry test tube, it produces Lead oxide(PbO) , Nitrogen dioxide( NO2) and oxygen(O2).

The lead nitrate is found to turn yellow due to the resultant product- lead oxide(PbO) and also there is evolution of a reddish brown gas which is nitrogen dioxide.

Answer 2

The correct option is d.

• When crystals of lead nitrate are heated strongly in a dry test tube lead oxide along with nitrogen dioxide and oxygen is formed.
• The reaction is-
• $2Pb(NO_3)_2\rightarrow 2PbO+4NO_2+O_2$
• In this reaction, a yellow residue of PbO is left and a brown coloured gas nitrogen dioxide is evolved.
• Thus the correct option is d) a yellow residue is left.