Hydrogen sulphide reacts with salts of various metals forming corresponding sulphides. Which of the following sulphides is precipited in acidic medium?

Options

A. `Co`
B. `Mn`
C. `Fe`
D. `Cu`

Answer

4

Explanation

Sulphides of `Hg, Ag, Pb, Cu, Bi, Cd, As, Sd`and `Sn` are preccipttated in acidic medium:
`{:(HgS",",CuS",",PbS,rarr,"Black"),(,,Bi_(2)S_(3),rarr,"Brown"),(,,CdS,rarr,"Yellow"):}}{:(),("Isoluble in yellow"),("ammonium sulphide"),():}`
`{:(,SnS_(2)",",As_(2)S_(3),rarr,"Yellow"),(,,sb_(2)S_(3),rarr,"Orange"),(,,SnS,rarr,"Chocolate"):}}{:(),("Soluble in yellow"),("ammonium sulphide"),():}`
Sulphides of `Zn, Co, Ni, Mn`, and `Fe` are precipated in alkanie medium:
`{:(CoS),(NiS):}}"Black "{:(ZnS-"White"),(MnS-"Flesh coloured"):}`
Sulphides of `Cr, Al, Mg, Ba, Sr, Ca, K` and `Na` are precipitated neither in acidic nor in alkaline medium.