Define (or) explain the following term: Precipitation
This question has multiple correct options
A.Diffusion in a solid
B.Reaction occurs in gaseous medium
C.Creation of a solid in a solution
D.None of these

Hint: We know that in double displacement reactions, when the cations and the anions switch between two reactants, new products are formed. In order for the reaction to occur, one of the products is usually a solid precipitate, a gas or a molecular compound.

Complete step by step answer:

We must remember that the term “Precipitation” refers to a chemical reaction, which occurs in aqueous solution when two ions attach together to form an insoluble salt that is called as the precipitate.
A precipitation reaction could take place when two solutions consisting of different salts are mixed, and a cation/anion pair in the resulting combined solution produces an insoluble salt; this salt then precipitates out of solution.
A common laboratory example of a precipitation reaction is reaction of Silver nitrate with potassium chloride.
Aqueous silver nitrate \[\left( {AgNO{ _3}} \right)\] is added to a solution having potassium chloride $\left( {KCl} \right)$ and the precipitation of a white solid, silver chloride $\left( {AgCl} \right)$ is seen.
We can write the chemical reaction as,
$AgN{O_3}\left( {aq} \right) + KCl\left( {aq} \right)\xrightarrow{{}}AgCl\left( s \right) + KN{O_3}\left( {aq} \right)$
A precipitate is an insoluble solid, which emerges from liquid solution and emergence of the insoluble solid from solution is called precipitation.
The liquid which causes the formation of solid is called as precipitant.
We can say precipitation is a diffusion of a solid, and creation of a solid in a solution.
Therefore, Option (A) and (C) are correct.
Combustion reactions generally take place in a gaseous medium. Therefore, Option (B) is incorrect.


Note:
We also know that the precipitation reaction helps in determining a specific element present in the given solution. These reactions monitor the formation of a precipitate when a certain chemical is added to solutions. We can use precipitation reactions for the extraction of magnesium from seawater. We can also use precipitation reactions in the treatment of wastewater. Precipitation reactions depend on concentration of the solution, buffer solution, temperature etc.