Chlorine was discovered by

When a few drops of concentrated $HCl$ are added to bleaching powder,which of the following is produced?

Which of the following is not a pseudo-halide ion?

$HI$ cannot be prepared by the reaction of concentrated $H_2SO_4$ with $KI$ because:

Fluorine reacts with water to produce

$NaCl$ (solid) $+ K_2Cr_2O_7$ (solid) $+$ conc. $H_2SO_4 \xrightarrow{\text{warm}} X$. Reddish brown fumes of $X$. The oxidation state of central atom in compound $X$ is