CBSE Class 10 Science 2023 Outside Delhi Set 2

Question : 7 of 12

Marks: +1, -0

A metal nitrate 'A' on heating gives a metal oxide along with evolution of a brown coloured gas '

B

' and a colourless gas, which helps in burning. Aqueous solution of '

A

' when reacted with potassium iodide forms a yellow precipitate.
(a) Identify '

A

' and '

B

'
(b) Name the types of the reactions involved in the above statement .

Solution:

The metal in compound

{\A}

is lead

( {\Pb})

. Therefore, we can write
Reaction 1 as:

2 {\Pb} ( {\NO}_3) _2 {→}↖{∆} 2 {\PbO}+4 {\NO}_2+ {\O}_2

Reaction 2:

{\Pb} ( {\NO}_3) _2+2 {\KI} → {\Pbl}_2+2 {\KNO}_3

Compound A-Lead nitrate:

{\Pb} ( {\NO}_3) _2

Compound B-Nitrogen dioxide-

{\NO}_2

Reaction 1 is thermal decomposition, whereas, reaction 2 is double decomposition reaction.

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