Which of the following gives the chromyl chloride test?

Which one of the following metals will give blue ash when its salt is heated with $Na_2CO_3$ solid and $Co(NO_3)_2$ on a charcoal piece?

Which metal ion gives a violet bead in the borax bead test?

While preparing crystals of Mohr's salt,dil. $H_2SO_4$ is added to a mixture of ferrous sulphate and ammonium sulphate,before dissolving this mixture in water,dil. $H_2SO_4$ is added here to:

$A$ 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

If steel is heated to a temperature well below red heat and is then cooled slowly,the process is called