What is the formula of microcosmic salt?

Assign $A, B, C, D$ from the given type of reaction.
$Na_2CO_3 + KNO_3 \longrightarrow$ No reaction

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2KI + FeCl_2 \longrightarrow$ No reaction

Which of the following gives the chromyl chloride test?

Which ion gives a violet-coloured bead in the borax bead test?

$A$ 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