Chlorine (Cl2) bleaches a substance permanently because it is due to oxidation but sulphure dioxide (SO2) does it temporarily because it is due to reduction.
Related Questions:
The inertness to chemical reactivity of noble gases is attributed to the following reasons:
(1)The noble gases except helium (1s2) have completely filled ns2np6 electronic configuration in their valence shell.
(2) They have high ionisation enthalpy and more positive electron gain enthalpy.