Question

Which of the following option is correct for the chemical reaction when two compounds exchange their ions to form two new compounds is called:
(A) Displacement reaction
(B) Combination reaction
(C) Double displacement reaction
(D) Redox reaction

Answer 1

Hint :A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation.

Complete Step By Step Answer:
Option 1:
Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and nonmetals take part in displacement reactions.
 $ A + B - C \to A - C + B $
Therefore, option 1 is incorrect.
Option 2:
A combination reaction is a general category of chemical reactions. It may be defined as a chemical reaction in which two or more substances combine to form a single substance under suitable conditions.
Combination reactions are also known as synthesis, because in these reactions new substances are synthesized.
 $ A + B \to C $
Therefore, option 2 is incorrect.
Option 3:
Double displacement reactions may be defined as the chemical reactions in which one component each of both the reacting molecules is exchanged to form the products. During this reaction, the cations and anions of two different compounds switch places, forming two entirely different compounds.
Double displacement reactions generally take place in aqueous solutions in which the ions precipitate and there is an exchange of ions.
 $ AB + CD \to AD + CB $
Therefore, option 3 is correct.
Option 4:
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron.
Therefore, option 4 is incorrect.

Note :
Double displacement reactions can be further classified as neutralization, precipitation and gas formation reactions. Neutralization reactions are the acid – base reaction which results in the formation of salt. Precipitation is the formation of a solid in a solution or inside another solid during a chemical reaction. Gas formation reactions are those where a product is obtained in gaseous state.