What is the reason for the bleaching action of chlorine?

Aluminium trifluoride is insoluble in anhydrous $HF$ but dissolves on addition of $NaF$. Aluminium trifluoride precipitates out of the resulting solution when gaseous $BF_3$ is bubbled through. Give reasons.

One gas bleaches the colour of flowers by reduction while the other by oxidation,the two gases respectively are

In the halogen group,fluorine has the highest electronegativity according to the Pauling scale,yet its electron gain enthalpy is less negative than that of chlorine. This is because ....

Which of the following properties of halogens increase with increasing atomic number?
$(I)$ Ionization energy $(II)$ Ionic radius
$(III)$ Bond energy of the $X_2$ molecule $(IV)$ Enthalpy of vaporisation

$NaCl$ (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