$Cl_{2}O_{7}$ is the anhydride of

Give two examples to show the anomalous behaviour of fluorine.

Which of the following sets represents the correct order of acidity?

The reaction of concentrated $HNO_3$ with iodine produces ....

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.

The electronic configuration of halogen is