(a) In vapour state, sulphur partly exists as `S_2` molecules and `S_2` molecule like `O_2` molecule has two unpaired electrons in the antibonding `pi^**-orbitals` and exhibits paramagnetic nature.
(b) This is because of higher electronegativity of flurine than oxygen. In naming a compound, the electronegative element is taken first, thus, the compounds of fluorides and fluorine oxides.
(c) Sulphur combines with sodium sulphite and forms sodium thiosulphate which is soluble in water and hence `S` disappears.
