Which of the following gives the chromyl chloride test?

Identify the type of precipitate formed in the following reaction: $(NH_4)_2SO_4 + Ba(OH)_2 \longrightarrow BaSO_4 \downarrow + 2NH_3 \uparrow$

Which of the following cations cannot give a borax bead test?

Which pair of cations can be identified by the borax bead test?

On performing a borax-bead test with a given inorganic mixture for qualitative analysis,the colour of the bead was found to be emerald green both in oxidising and reducing flame. It indicates the possibility of the presence of

$A$ chemistry student trying to detect the metallic ion in a salt,makes a paste on a clean platinum wire loop of the salt with concentrated $HCl$. When he takes a small amount of this paste and keeps it in a non-luminous Bunsen flame,the colour of the flame changes to grassy green. He should,therefore,conclude that the metal is