Question

Concentrated is used in the confirmatory test for sulphate ion.

• A. $HCl$
• B. $H_{2}S{O}_4$
• C. $HN{O}_3$

Answer 1

The correct option is A $HCl$

Concentrated hydrochloric acid is used in the confirmatory test for sulphate ions.
In this test, a white precipitate of metal sulphate which does not dissolve in concentrated HCl is used to confirm the presence of $S{O}_4^2-$ ion.
However, $H_{2}S{O}_4$ cannot be used testing as it already contains $S{O}_4^2-$ ions which leads to a false positive test by increasing its quantity.
Similarly, NaOH is a strong base which release $O{H}^{-}$ anion making it difficult for the $S{O}_4^2-$ anion.