Question

Under which two conditions do decomposition reaction normally take place?
give one example of each.

Answer 1

Decomposition reaction mainly take place in three conditions:-

1. In the presence of sunlight i.e. when silver chloride is put in sunlight, it decomposes into silver metal and chlorine gas.
2. In the presence of heat i.e. when lead nitrate is heated, it decomposes into lead oxide, nitrogen dioxide and oxygen.
3. By passing electricity through the compound i.e. when electricity is passed in water, it decomposes into hydrogen and oxygen.

Answer 2

(1.) Decomposition on heating

Calcium carbonate when heated gives quicklime (CaO) and carbon dioxide

$CaCO _{3 } →CaO + CO _{2}$

(2.) Decomposition by light

Silver chloride decomposes to silver and chlorine in presence of sunlight

$2AgCl→2Ag+Cl _{2}$

(3). Decomposition by electricity

Water on electrolysis gives hydrogen and oxygen

$2H_{2}</p><p>O→2H_{2} +O _{2}$