Question

A white sodium salt dissolves readily in water to give a solution which is neutral to litmus. When silver nitrate solution is added to the aforementioned solution, a white precipitate is obtained which does not dissolve in dil .nitric acid.
The anion is
A) $C{O_3}^{2 - }$
B) ${S^{2 - }}$
C) $S{O_4}^{2 - }$
D) $C{l^ - }$

Answer 1

We should firstly see the reactions of all the ions when they are taken as sodium salts and how they react when silver nitrate is added to them and how they further react when dilute nitric acid is added to it. accordingly if ion will show all the same reactions then it will take to form sodium salt and further it will carry the reaction in the same way as stated.

Complete step-by-step answer: Firstly we are given that the a white sodium salt dissolves readily in water to give a solution which is neutral to litmus. So, we are assuming the sodium salt to be the sodium chloride . This is so because the statement further states that when silver nitrate is added to the above solution then a white precipitate is obtained which further is undissolved in dilute nitric acid. So when we look at the sodium chloride $C{l^ - }$ ions reacts with $AgN{O_3}$to form a white curdy ppt of $AgCl$ which is water insoluble and also, insoluble in dilute ammonia due to the formation of soluble complex.
Further when we consider sodium carbonate as the solid salt then we will find out that the solid precipitate is formed when the silver nitrate is added to the above solution.
Also, if we consider sodium sulphate and then silver nitrate is added to it we find an ionic compound which is insoluble in an aqueous solution.
We conclude that the sodium salt is none other than the sodium chloride.

Note: Since, the reaction of silver nitrate forms white precipitate so, only silver chloride gives white precipitate. Hence, salt must be sodium chloride.