The salt of an alkali metal gives yellow colour in the flame test. Also its aqueous solution gives an insoluble white precipitate with barium chloride in acid medium. The salt is

Options

A. NaCl
B. `K_2SO_4`
C. `Na_2O and O_3`
D. `Li_2SO_4`

Answer

C

Explanation

Since the alkali metal salt gives a yellow colour in the flame, it must be sodium salt. Further, since the salt gives an insoluble white ppt. with `BaCl_2` in acidic medium, it must be sodium sulphate `Na_2SO_4`.
`Na_2SO_4 + BaCl_2 rarr underset("White ppt")(BaSO_4) darr + 2NaCl`