Sometimes yellow turbidity appears while passing `H_(2)S` gas even in the absence of II group radicals. This is because of

Options

A. sulphur is present in the mixture as impurity
B. (IV) grou radicals are precipitated as sulphides
C. the oxidation of `H_(2)S` gas by some acid radicals
D. III group radicals are precipitated as hydroxides

Answer

C

Explanation

On passing `H_(2)S` gas into first group filtrate sometimes yellow turbidity appears even in the absence of II group radicals, this is because of the oxidation of `H_(2)S` gas by some acid radicals and form colloidal solution of sulphur.
`Fe_((aq.))^(3+)underset(("redox reaction"))overset(H_(2)S//H^(+))to Fe_((aq.))^(2+)+Sdarr`