Write balanced chemical equations for the following:
$(i)$ $NaCl$ is heated with concentrated sulphuric acid $(H_{2}SO_{4})$ in the presence of manganese dioxide $(MnO_{2})$.
$(ii)$ Chlorine gas $(Cl_{2})$ is passed into an aqueous solution of sodium iodide $(NaI)$.

$K_2Cr_2O_7 +$ conc. $H_2SO_4 + NaCl \rightarrow$ red orange vapours. Here red orange vapours are of :

When chlorine gas is passed through an aqueous solution of a potassium halide in the presence of chloroform,a violet colouration is obtained. On passing more of chlorine water,the violet colour disappears and the solution becomes colourless. This test confirms the presence of ........... in the aqueous solution.

Which of the following elements belongs to the halogen group?

$ClF_5$ at room temperature is a:

Sea is the greatest source of some halogens. Comment.