In the flame test of a mixture of salts,a green flame with a blue centre was observed. Which one of the following cations may be present?

Which of the following statement$(s)$ is (are) correct when a mixture of $NaCl$ and $K_{2}Cr_{2}O_{7}$ is gently warmed with conc. $H_{2}SO_{4}?$

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

Starch paper is used to test for the presence of

Which of the following gives the chromyl chloride test?