Which product is formed when fluorine reacts with hot and concentrated sodium hydroxide?

$HI$ cannot be prepared by the action of conc. $H_2SO_4$ on $KI$ because:

Which of the following statements is not true for halogens?

Which of the following statements regarding halogens is correct?

When a mixture of solid $NaCl$ and solid $K_2Cr_2O_7$ is heated with concentrated $H_2SO_4$,orange-red vapours are evolved. These vapours are of which compound?

Chlorine reacts with hot and concentrated $NaOH$ and produces compounds $(X)$ and $(Y)$. Compound $(X)$ gives a white precipitate with silver nitrate solution. The average bond order between $Cl$ and $O$ atoms in $(Y)$ is