Why conc. H2SO4 can not be used for the preparation of H2S gas?​

Hydrogen sulphide gas cannot be dried using sulphuric acid as H2S gas is oxidised by sulphuric acid to Sulphur

Explanation:

H2S gas has chemical action with acid and hence it reacts with it

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.