Question

In a double displacement reaction such as the reaction between sodium sulphate solution and barium chloride solution:

(A) exchange of atoms takes place
(B) exchange of ions takes place
(C) a precipitate is produced
(D) an insoluble salt is produced
The correct option is:
1.(B) and (D)
2.(A) and (C)
3.Only (B)
4.(B), (C) and (D)

Answer 1

In a chemical reaction there is an ion exchange process taking place. And due to this ion exchange process an insoluble solid is formed during the reaction which results in the formation of a precipitate. In the reaction only ions react not atoms.

Complete step by step answer:
When sodium sulphate reacts with barium chloride a double displacement reaction takes place and there is a formation of barium sulphate and sodium chloride. In the above reaction the compound formed, i.e. , barium sulphate is an insoluble product and is a precipitate. $N{a_2}S{O_4}(aq) + BaC{l_2}(aq) \to BaS{O_4}(s) \downarrow + 2NaCl(aq)$
In the above reaction exchange of ions takes place.
Hence option (D) is the correct answer .

Additional Information:
Double displacement reaction: Double displacement reactions are the reactions in which two compounds react with each other by an exchange of ions and form two new compounds. In a double replacement reaction, positive-negative ion exchange takes place. It is represented by the general equation.
$A + B \to C + D$
In a double displacement reaction, atoms of two different compounds switch their places. The reactants are two different compounds and the products are other two different compounds. Double displacement reactions are also called double replacement reactions.
$N{a_2}S{O_4}(aq) + BaC{l_2}(aq) \to BaS{O_4}(s) \downarrow + 2NaCl(aq)$
Many of the double displacement reactions occur in between ionic compounds that have been dissolved in water.
Precipitate: Precipitation is the process of creation of a solid from a solution. When the reaction of a liquid solution occurs, the solid formed during the process is called the 'precipitate'. The chemical that results in the solid to form is called the 'precipitant'.

Note:
There are various types of reaction. Also In a chemical reaction, ion exchange takes place not the atoms. Also in a double displacement reaction both the ion gets displaced unlike a single displacement reaction.