Question

The salt of an alkali metal gives violet colour in the flame test. Its aqueous solution gives a white precipitate with barium chloride in hydrochloric acid medium. The salt is:

• A. $K_{2}S{O}_4$
• B. $KCl$
• C. $N{a}_{2}S{O}_4$
• D. $K_{2}C{O}_3$
• E. $LiS{O}_4$

Answer 1

Answer: (A)

$K_{2}S{O}_4$

The salt gives violet colour in the flame test, which shows the presence of potassium ion $\left(K^{+}\right)$ in it. Further, the aqueous solution of salt gives white precipitate with $BaC{l}_2$ in acidic medium, so it must contain sulphate ion $\left(S{O}_4^{2-}\right)$ and the precipitate is of $BaS{O}_4$.

Thus, the salt is $K_{2}S{O}_4$.