Question

Which of the following reaction is characterised by the release of brown

fumes?

(a) Zn + H2SO4 ----> ZnSO4 + H2

(b) Na2CO3 + H2SO4 ----> Na2SO4 + H2O + CO2

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

(d) 2Ca(NO3)2 ----> 2CaO + 2NO2 + O2​

Answer 1

Required Answer:-

Fumes coming out as a result of a reaction is observed when any gas is released with a lot of pressure. Brown fumes means any gas which is brown in colour$.$

Now,

Come to the reactions listed in the question. In the product side, Hydrogen, Carbon dioxide, Nitrogen dioxode and Oxygen gas are the gaseous products. And among them, NO2 is a brown in colour.

Hence,

Brown fumes will be observed in:

• (c) 2Pb(NO3)2 ----> 2PbO + 4NO2 + O2
• (d) 2Ca(NO3)2 ----> 2CaO + 2NO2 + O2

Answer 2

Answer:

Required Answer :-

Option C

$\sf \: 2Pb(NO3) _2 - 2PbO + 4NO _ 2 + O _2$

Know More :-

A chemical reaction is a reaction in which two or more element mixes and form a new substance. In a chemical reaction there is few change is property of substance.

Some characterstics :-

• Temperature changes
• Property changes
• Gas evoluate