Assertion : Sb (III) is not precipitated as sulphide when in its alkaline solution `H_(2)S` is passed.
Reason : The concentration of `S^(2-)` ion in alkaline medium is inadequate for precipitation.

Options

A. If both assertion and reason are true, and reason is the true explanation of the assertion.
B. If both assertion and reason are true, but reason is not the true explanation of the assertion.
C. If aasertion is true, but reason is false.
D. If both assertion and reason are false.

Answer

C

Explanation

Correct A. The pH at the end point of only a strong acid with strong base is 7.
Correct R. Sb (III) is precipitated (in Group IIB) by `H_(2)S` in acidic medium (dil . HCl) . In acidic medium, `S^(2-)` concentration decreases so that radicals of Group IV are not precipitated. In alkaline medium, `S^(2-)` ion concentration increases and not decreases.